diff --git a/prelude.md b/prelude.md
index b0473c6..ada9f28 100644
--- a/prelude.md
+++ b/prelude.md
@@ -56,7 +56,7 @@ You can see what this looks like in the last clause of `add`: `((x1, y1), (x2, y
 [any?](#any)&nbsp;&nbsp;&nbsp; [append](#append)&nbsp;&nbsp;&nbsp; [at](#at)&nbsp;&nbsp;&nbsp; [butlast](#butlast)&nbsp;&nbsp;&nbsp; [coll?](#coll)&nbsp;&nbsp;&nbsp; [concat](#concat)&nbsp;&nbsp;&nbsp; [count](#count)&nbsp;&nbsp;&nbsp; [each!](#each)&nbsp;&nbsp;&nbsp; [empty?](#empty)&nbsp;&nbsp;&nbsp; [filter](#filter)&nbsp;&nbsp;&nbsp; [first](#first)&nbsp;&nbsp;&nbsp; [fold](#fold)&nbsp;&nbsp;&nbsp; [join](#join)&nbsp;&nbsp;&nbsp; [keep](#keep)&nbsp;&nbsp;&nbsp; [last](#last)&nbsp;&nbsp;&nbsp; [list](#list)&nbsp;&nbsp;&nbsp; [list?](#list)&nbsp;&nbsp;&nbsp; [map](#map)&nbsp;&nbsp;&nbsp; [ordered?](#ordered)&nbsp;&nbsp;&nbsp; [random](#random)&nbsp;&nbsp;&nbsp; [range](#range)&nbsp;&nbsp;&nbsp; [rest](#rest)&nbsp;&nbsp;&nbsp; [second](#second)&nbsp;&nbsp;&nbsp; [sentence](#sentence)&nbsp;&nbsp;&nbsp; [slice](#slice)
 
 ### Math
-[abs](#abs)&nbsp;&nbsp;&nbsp; [add](#add)&nbsp;&nbsp;&nbsp; [angle](#angle)&nbsp;&nbsp;&nbsp; [atan/2](#atan/2)&nbsp;&nbsp;&nbsp; [between?](#between)&nbsp;&nbsp;&nbsp; [ceil](#ceil)&nbsp;&nbsp;&nbsp; [cos](#cos)&nbsp;&nbsp;&nbsp; [dec](#dec)&nbsp;&nbsp;&nbsp; [deg/rad](#deg/rad)&nbsp;&nbsp;&nbsp; [deg/turn](#deg/turn)&nbsp;&nbsp;&nbsp; [dist](#dist)&nbsp;&nbsp;&nbsp; [div](#div)&nbsp;&nbsp;&nbsp; [div/0](#div/0)&nbsp;&nbsp;&nbsp; [div/safe](#div/safe)&nbsp;&nbsp;&nbsp; [even?](#even)&nbsp;&nbsp;&nbsp; [floor](#floor)&nbsp;&nbsp;&nbsp; [gt?](#gt)&nbsp;&nbsp;&nbsp; [gte?](#gte)&nbsp;&nbsp;&nbsp; [heading/vector](#heading/vector)&nbsp;&nbsp;&nbsp; [inc](#inc)&nbsp;&nbsp;&nbsp; [inv](#inv)&nbsp;&nbsp;&nbsp; [inv/0](#inv/0)&nbsp;&nbsp;&nbsp; [inv/safe](#inv/safe)&nbsp;&nbsp;&nbsp; [lt?](#lt)&nbsp;&nbsp;&nbsp; [lte?](#lte)&nbsp;&nbsp;&nbsp; [max](#max)&nbsp;&nbsp;&nbsp; [min](#min)&nbsp;&nbsp;&nbsp; [mod](#mod)&nbsp;&nbsp;&nbsp; [mod/0](#mod/0)&nbsp;&nbsp;&nbsp; [mod/safe](#mod/safe)&nbsp;&nbsp;&nbsp; [mult](#mult)&nbsp;&nbsp;&nbsp; [neg](#neg)&nbsp;&nbsp;&nbsp; [neg?](#neg)&nbsp;&nbsp;&nbsp; [odd?](#odd)&nbsp;&nbsp;&nbsp; [pi](#pi)&nbsp;&nbsp;&nbsp; [pos?](#pos)&nbsp;&nbsp;&nbsp; [rad/deg](#rad/deg)&nbsp;&nbsp;&nbsp; [rad/turn](#rad/turn)&nbsp;&nbsp;&nbsp; [random](#random)&nbsp;&nbsp;&nbsp; [random\_int](#random\_int)&nbsp;&nbsp;&nbsp; [range](#range)&nbsp;&nbsp;&nbsp; [round](#round)&nbsp;&nbsp;&nbsp; [sin](#sin)&nbsp;&nbsp;&nbsp; [sqrt](#sqrt)&nbsp;&nbsp;&nbsp; [sqrt/safe](#sqrt/safe)&nbsp;&nbsp;&nbsp; [square](#square)&nbsp;&nbsp;&nbsp; [sub](#sub)&nbsp;&nbsp;&nbsp; [sum\_of_squares](#sum\_of_squares)&nbsp;&nbsp;&nbsp; [tan](#tan)&nbsp;&nbsp;&nbsp; [tau](#tau)&nbsp;&nbsp;&nbsp; [turn/deg](#turn/deg)&nbsp;&nbsp;&nbsp; [turn/rad](#turn/rad)&nbsp;&nbsp;&nbsp; [zero?](#zero)
+[abs](#abs)&nbsp;&nbsp;&nbsp; [add](#add)&nbsp;&nbsp;&nbsp; [angle](#angle)&nbsp;&nbsp;&nbsp; [atan/2](#atan2)&nbsp;&nbsp;&nbsp; [between?](#between)&nbsp;&nbsp;&nbsp; [ceil](#ceil)&nbsp;&nbsp;&nbsp; [cos](#cos)&nbsp;&nbsp;&nbsp; [dec](#dec)&nbsp;&nbsp;&nbsp; [deg/rad](#degrad)&nbsp;&nbsp;&nbsp; [deg/turn](#degturn)&nbsp;&nbsp;&nbsp; [dist](#dist)&nbsp;&nbsp;&nbsp; [div](#div)&nbsp;&nbsp;&nbsp; [div/0](#div0)&nbsp;&nbsp;&nbsp; [div/safe](#divsafe)&nbsp;&nbsp;&nbsp; [even?](#even)&nbsp;&nbsp;&nbsp; [floor](#floor)&nbsp;&nbsp;&nbsp; [gt?](#gt)&nbsp;&nbsp;&nbsp; [gte?](#gte)&nbsp;&nbsp;&nbsp; [heading/vector](#headingvector)&nbsp;&nbsp;&nbsp; [inc](#inc)&nbsp;&nbsp;&nbsp; [inv](#inv)&nbsp;&nbsp;&nbsp; [inv/0](#inv0)&nbsp;&nbsp;&nbsp; [inv/safe](#invsafe)&nbsp;&nbsp;&nbsp; [lt?](#lt)&nbsp;&nbsp;&nbsp; [lte?](#lte)&nbsp;&nbsp;&nbsp; [max](#max)&nbsp;&nbsp;&nbsp; [min](#min)&nbsp;&nbsp;&nbsp; [mod](#mod)&nbsp;&nbsp;&nbsp; [mod/0](#mod0)&nbsp;&nbsp;&nbsp; [mod/safe](#modsafe)&nbsp;&nbsp;&nbsp; [mult](#mult)&nbsp;&nbsp;&nbsp; [neg](#neg)&nbsp;&nbsp;&nbsp; [neg?](#neg)&nbsp;&nbsp;&nbsp; [odd?](#odd)&nbsp;&nbsp;&nbsp; [pi](#pi)&nbsp;&nbsp;&nbsp; [pos?](#pos)&nbsp;&nbsp;&nbsp; [rad/deg](#raddeg)&nbsp;&nbsp;&nbsp; [rad/turn](#radturn)&nbsp;&nbsp;&nbsp; [random](#random)&nbsp;&nbsp;&nbsp; [random\_int](#random\_int)&nbsp;&nbsp;&nbsp; [range](#range)&nbsp;&nbsp;&nbsp; [round](#round)&nbsp;&nbsp;&nbsp; [sin](#sin)&nbsp;&nbsp;&nbsp; [sqrt](#sqrt)&nbsp;&nbsp;&nbsp; [sqrt/safe](#sqrtsafe)&nbsp;&nbsp;&nbsp; [square](#square)&nbsp;&nbsp;&nbsp; [sub](#sub)&nbsp;&nbsp;&nbsp; [sum\_of_squares](#sum\_of_squares)&nbsp;&nbsp;&nbsp; [tan](#tan)&nbsp;&nbsp;&nbsp; [tau](#tau)&nbsp;&nbsp;&nbsp; [turn/deg](#turndeg)&nbsp;&nbsp;&nbsp; [turn/rad](#turnrad)&nbsp;&nbsp;&nbsp; [zero?](#zero)
 
 ### Results
 [err](#err)&nbsp;&nbsp;&nbsp; [err?](#err)&nbsp;&nbsp;&nbsp; [ok](#ok)&nbsp;&nbsp;&nbsp; [ok?](#ok)&nbsp;&nbsp;&nbsp; [unwrap!](#unwrap)&nbsp;&nbsp;&nbsp; [unwrap\_or](#unwrap\_or)
@@ -65,19 +65,19 @@ You can see what this looks like in the last clause of `add`: `((x1, y1), (x2, y
 [any?](#any)&nbsp;&nbsp;&nbsp; [append](#append)&nbsp;&nbsp;&nbsp; [coll?](#coll)&nbsp;&nbsp;&nbsp; [concat](#concat)&nbsp;&nbsp;&nbsp; [contains?](#contains)&nbsp;&nbsp;&nbsp; [count](#count)&nbsp;&nbsp;&nbsp; [empty?](#empty)&nbsp;&nbsp;&nbsp; [omit](#omit)&nbsp;&nbsp;&nbsp; [random](#random)&nbsp;&nbsp;&nbsp; [set](#set)&nbsp;&nbsp;&nbsp; [set?](#set)
 
 ### Strings
-[any?](#any)&nbsp;&nbsp;&nbsp; [chars](#chars)&nbsp;&nbsp;&nbsp; [chars/safe](#chars/safe)&nbsp;&nbsp;&nbsp; [concat](#concat)&nbsp;&nbsp;&nbsp; [count](#count)&nbsp;&nbsp;&nbsp; [downcase](#downcase)&nbsp;&nbsp;&nbsp; [empty?](#empty)&nbsp;&nbsp;&nbsp; [join](#join)&nbsp;&nbsp;&nbsp; [sentence](#sentence)&nbsp;&nbsp;&nbsp; [show](#show)&nbsp;&nbsp;&nbsp; [slice](#slice)&nbsp;&nbsp;&nbsp; [split](#split)&nbsp;&nbsp;&nbsp; [string](#string)&nbsp;&nbsp;&nbsp; [string?](#string)&nbsp;&nbsp;&nbsp; [strip](#strip)&nbsp;&nbsp;&nbsp; [trim](#trim)&nbsp;&nbsp;&nbsp; [upcase](#upcase)&nbsp;&nbsp;&nbsp; [words](#words)
+[any?](#any)&nbsp;&nbsp;&nbsp; [chars](#chars)&nbsp;&nbsp;&nbsp; [chars/safe](#charssafe)&nbsp;&nbsp;&nbsp; [concat](#concat)&nbsp;&nbsp;&nbsp; [count](#count)&nbsp;&nbsp;&nbsp; [downcase](#downcase)&nbsp;&nbsp;&nbsp; [empty?](#empty)&nbsp;&nbsp;&nbsp; [join](#join)&nbsp;&nbsp;&nbsp; [sentence](#sentence)&nbsp;&nbsp;&nbsp; [show](#show)&nbsp;&nbsp;&nbsp; [slice](#slice)&nbsp;&nbsp;&nbsp; [split](#split)&nbsp;&nbsp;&nbsp; [string](#string)&nbsp;&nbsp;&nbsp; [string?](#string)&nbsp;&nbsp;&nbsp; [strip](#strip)&nbsp;&nbsp;&nbsp; [trim](#trim)&nbsp;&nbsp;&nbsp; [upcase](#upcase)&nbsp;&nbsp;&nbsp; [words](#words)
 
 ### Tuples
 [any?](#any)&nbsp;&nbsp;&nbsp; [at](#at)&nbsp;&nbsp;&nbsp; [coll?](#coll)&nbsp;&nbsp;&nbsp; [count](#count)&nbsp;&nbsp;&nbsp; [empty?](#empty)&nbsp;&nbsp;&nbsp; [first](#first)&nbsp;&nbsp;&nbsp; [last](#last)&nbsp;&nbsp;&nbsp; [ordered?](#ordered)&nbsp;&nbsp;&nbsp; [rest](#rest)&nbsp;&nbsp;&nbsp; [second](#second)&nbsp;&nbsp;&nbsp; [tuple?](#tuple)
 
 ### Turtle graphics
-[back!](#back)&nbsp;&nbsp;&nbsp; [background!](#background)&nbsp;&nbsp;&nbsp; [bk!](#bk)&nbsp;&nbsp;&nbsp; [clear!](#clear)&nbsp;&nbsp;&nbsp; [colors](#colors)&nbsp;&nbsp;&nbsp; [fd!](#fd)&nbsp;&nbsp;&nbsp; [forward!](#forward)&nbsp;&nbsp;&nbsp; [goto!](#goto)&nbsp;&nbsp;&nbsp; [heading](#heading)&nbsp;&nbsp;&nbsp; [heading/vector](#heading/vector)&nbsp;&nbsp;&nbsp; [home!](#home)&nbsp;&nbsp;&nbsp; [left!](#left)&nbsp;&nbsp;&nbsp; [lt!](#lt)&nbsp;&nbsp;&nbsp; [pc!](#pc)&nbsp;&nbsp;&nbsp; [pd!](#pd)&nbsp;&nbsp;&nbsp; [pencolor](#pencolor)&nbsp;&nbsp;&nbsp; [pencolor!](#pencolor)&nbsp;&nbsp;&nbsp; [pendown!](#pendown)&nbsp;&nbsp;&nbsp; [pendown?](#pendown)&nbsp;&nbsp;&nbsp; [penup!](#penup)&nbsp;&nbsp;&nbsp; [penwidth](#penwidth)&nbsp;&nbsp;&nbsp; [penwidth!](#penwidth)&nbsp;&nbsp;&nbsp; [position](#position)&nbsp;&nbsp;&nbsp; [pu!](#pu)&nbsp;&nbsp;&nbsp; [pw!](#pw)&nbsp;&nbsp;&nbsp; [render\_turtle!](#render\_turtle)&nbsp;&nbsp;&nbsp; [reset\_turtle!](#reset\_turtle)&nbsp;&nbsp;&nbsp; [right!](#right)&nbsp;&nbsp;&nbsp; [rt!](#rt)&nbsp;&nbsp;&nbsp; [turtle\_state](#turtle\_state)
+[back!](#back)&nbsp;&nbsp;&nbsp; [background!](#background)&nbsp;&nbsp;&nbsp; [bk!](#bk)&nbsp;&nbsp;&nbsp; [clear!](#clear)&nbsp;&nbsp;&nbsp; [colors](#colors)&nbsp;&nbsp;&nbsp; [fd!](#fd)&nbsp;&nbsp;&nbsp; [forward!](#forward)&nbsp;&nbsp;&nbsp; [goto!](#goto)&nbsp;&nbsp;&nbsp; [heading](#heading)&nbsp;&nbsp;&nbsp; [heading/vector](#headingvector)&nbsp;&nbsp;&nbsp; [hideturtle!](#hideturtle)&nbsp;&nbsp;&nbsp; [home!](#home)&nbsp;&nbsp;&nbsp; [left!](#left)&nbsp;&nbsp;&nbsp; [loadstate!](#loadstate)&nbsp;&nbsp;&nbsp; [lt!](#lt)&nbsp;&nbsp;&nbsp; [pc!](#pc)&nbsp;&nbsp;&nbsp; [pd!](#pd)&nbsp;&nbsp;&nbsp; [pencolor](#pencolor)&nbsp;&nbsp;&nbsp; [pencolor!](#pencolor)&nbsp;&nbsp;&nbsp; [pendown!](#pendown)&nbsp;&nbsp;&nbsp; [pendown?](#pendown)&nbsp;&nbsp;&nbsp; [penup!](#penup)&nbsp;&nbsp;&nbsp; [penwidth](#penwidth)&nbsp;&nbsp;&nbsp; [penwidth!](#penwidth)&nbsp;&nbsp;&nbsp; [position](#position)&nbsp;&nbsp;&nbsp; [pu!](#pu)&nbsp;&nbsp;&nbsp; [pw!](#pw)&nbsp;&nbsp;&nbsp; [render\_turtle!](#render\_turtle)&nbsp;&nbsp;&nbsp; [reset\_turtle!](#reset\_turtle)&nbsp;&nbsp;&nbsp; [right!](#right)&nbsp;&nbsp;&nbsp; [rt!](#rt)&nbsp;&nbsp;&nbsp; [setheading!](#setheading)&nbsp;&nbsp;&nbsp; [showturtle!](#showturtle)&nbsp;&nbsp;&nbsp; [turtle\_state](#turtle\_state)
 
 ### Types and values
 [assoc?](#assoc)&nbsp;&nbsp;&nbsp; [bool?](#bool)&nbsp;&nbsp;&nbsp; [box?](#box)&nbsp;&nbsp;&nbsp; [coll?](#coll)&nbsp;&nbsp;&nbsp; [dict?](#dict)&nbsp;&nbsp;&nbsp; [eq?](#eq)&nbsp;&nbsp;&nbsp; [fn?](#fn)&nbsp;&nbsp;&nbsp; [keyword?](#keyword)&nbsp;&nbsp;&nbsp; [list?](#list)&nbsp;&nbsp;&nbsp; [neq?](#neq)&nbsp;&nbsp;&nbsp; [nil?](#nil)&nbsp;&nbsp;&nbsp; [number?](#number)&nbsp;&nbsp;&nbsp; [ordered?](#ordered)&nbsp;&nbsp;&nbsp; [set?](#set)&nbsp;&nbsp;&nbsp; [show](#show)&nbsp;&nbsp;&nbsp; [some](#some)&nbsp;&nbsp;&nbsp; [some?](#some)&nbsp;&nbsp;&nbsp; [string?](#string)&nbsp;&nbsp;&nbsp; [tuple?](#tuple)&nbsp;&nbsp;&nbsp; [type](#type)
     
 ## All functions, alphabetically
-[abs](#abs)&nbsp;&nbsp;&nbsp; [add](#add)&nbsp;&nbsp;&nbsp; [and](#and)&nbsp;&nbsp;&nbsp; [angle](#angle)&nbsp;&nbsp;&nbsp; [any?](#any)&nbsp;&nbsp;&nbsp; [append](#append)&nbsp;&nbsp;&nbsp; [assert!](#assert)&nbsp;&nbsp;&nbsp; [assoc](#assoc)&nbsp;&nbsp;&nbsp; [assoc?](#assoc)&nbsp;&nbsp;&nbsp; [at](#at)&nbsp;&nbsp;&nbsp; [atan/2](#atan/2)&nbsp;&nbsp;&nbsp; [back!](#back)&nbsp;&nbsp;&nbsp; [background!](#background)&nbsp;&nbsp;&nbsp; [between?](#between)&nbsp;&nbsp;&nbsp; [bg!](#bg)&nbsp;&nbsp;&nbsp; [bk!](#bk)&nbsp;&nbsp;&nbsp; [bool](#bool)&nbsp;&nbsp;&nbsp; [bool?](#bool)&nbsp;&nbsp;&nbsp; [box?](#box)&nbsp;&nbsp;&nbsp; [butlast](#butlast)&nbsp;&nbsp;&nbsp; [ceil](#ceil)&nbsp;&nbsp;&nbsp; [chars](#chars)&nbsp;&nbsp;&nbsp; [clear!](#clear)&nbsp;&nbsp;&nbsp; [coll?](#coll)&nbsp;&nbsp;&nbsp; [colors](#colors)&nbsp;&nbsp;&nbsp; [concat](#concat)&nbsp;&nbsp;&nbsp; [contains?](#contains)&nbsp;&nbsp;&nbsp; [cos](#cos)&nbsp;&nbsp;&nbsp; [count](#count)&nbsp;&nbsp;&nbsp; [dec](#dec)&nbsp;&nbsp;&nbsp; [deg/rad](#deg/rad)&nbsp;&nbsp;&nbsp; [deg/turn](#deg/turn)&nbsp;&nbsp;&nbsp; [dict](#dict)&nbsp;&nbsp;&nbsp; [dict?](#dict)&nbsp;&nbsp;&nbsp; [diff](#diff)&nbsp;&nbsp;&nbsp; [dissoc](#dissoc)&nbsp;&nbsp;&nbsp; [dist](#dist)&nbsp;&nbsp;&nbsp; [div](#div)&nbsp;&nbsp;&nbsp; [div/0](#div/0)&nbsp;&nbsp;&nbsp; [div/safe](#div/safe)&nbsp;&nbsp;&nbsp; [doc!](#doc)&nbsp;&nbsp;&nbsp; [downcase](#downcase)&nbsp;&nbsp;&nbsp; [each!](#each)&nbsp;&nbsp;&nbsp; [empty?](#empty)&nbsp;&nbsp;&nbsp; [eq?](#eq)&nbsp;&nbsp;&nbsp; [err](#err)&nbsp;&nbsp;&nbsp; [err?](#err)&nbsp;&nbsp;&nbsp; [even?](#even)&nbsp;&nbsp;&nbsp; [false?](#false)&nbsp;&nbsp;&nbsp; [fd!](#fd)&nbsp;&nbsp;&nbsp; [filter](#filter)&nbsp;&nbsp;&nbsp; [first](#first)&nbsp;&nbsp;&nbsp; [floor](#floor)&nbsp;&nbsp;&nbsp; [fn?](#fn)&nbsp;&nbsp;&nbsp; [fold](#fold)&nbsp;&nbsp;&nbsp; [forward!](#forward)&nbsp;&nbsp;&nbsp; [get](#get)&nbsp;&nbsp;&nbsp; [goto!](#goto)&nbsp;&nbsp;&nbsp; [gt?](#gt)&nbsp;&nbsp;&nbsp; [gte?](#gte)&nbsp;&nbsp;&nbsp; [heading](#heading)&nbsp;&nbsp;&nbsp; [heading/vector](#heading/vector)&nbsp;&nbsp;&nbsp; [hideturtle!](#hideturtle)&nbsp;&nbsp;&nbsp; [home!](#home)&nbsp;&nbsp;&nbsp; [inc](#inc)&nbsp;&nbsp;&nbsp; [inv](#inv)&nbsp;&nbsp;&nbsp; [inv/0](#inv/0)&nbsp;&nbsp;&nbsp; [inv/safe](#inv/safe)&nbsp;&nbsp;&nbsp; [join](#join)&nbsp;&nbsp;&nbsp; [keep](#keep)&nbsp;&nbsp;&nbsp; [keys](#keys)&nbsp;&nbsp;&nbsp; [keyword?](#keyword)&nbsp;&nbsp;&nbsp; [last](#last)&nbsp;&nbsp;&nbsp; [left!](#left)&nbsp;&nbsp;&nbsp; [list](#list)&nbsp;&nbsp;&nbsp; [list?](#list)&nbsp;&nbsp;&nbsp; [loadstate!](#loadstate)&nbsp;&nbsp;&nbsp; [lt!](#lt)&nbsp;&nbsp;&nbsp; [lt?](#lt)&nbsp;&nbsp;&nbsp; [lte?](#lte)&nbsp;&nbsp;&nbsp; [map](#map)&nbsp;&nbsp;&nbsp; [max](#max)&nbsp;&nbsp;&nbsp; [min](#min)&nbsp;&nbsp;&nbsp; [mod](#mod)&nbsp;&nbsp;&nbsp; [mod/0](#mod/0)&nbsp;&nbsp;&nbsp; [mod/safe](#mod/safe)&nbsp;&nbsp;&nbsp; [mult](#mult)&nbsp;&nbsp;&nbsp; [neg](#neg)&nbsp;&nbsp;&nbsp; [neg?](#neg)&nbsp;&nbsp;&nbsp; [neq?](#neq)&nbsp;&nbsp;&nbsp; [nil?](#nil)&nbsp;&nbsp;&nbsp; [not](#not)&nbsp;&nbsp;&nbsp; [odd?](#odd)&nbsp;&nbsp;&nbsp; [ok](#ok)&nbsp;&nbsp;&nbsp; [ok?](#ok)&nbsp;&nbsp;&nbsp; [omit](#omit)&nbsp;&nbsp;&nbsp; [or](#or)&nbsp;&nbsp;&nbsp; [ordered?](#ordered)&nbsp;&nbsp;&nbsp; [pc!](#pc)&nbsp;&nbsp;&nbsp; [pd!](#pd)&nbsp;&nbsp;&nbsp; [pencolor](#pencolor)&nbsp;&nbsp;&nbsp; [pencolor!](#pencolor)&nbsp;&nbsp;&nbsp; [pendown!](#pendown)&nbsp;&nbsp;&nbsp; [pendown?](#pendown)&nbsp;&nbsp;&nbsp; [penup!](#penup)&nbsp;&nbsp;&nbsp; [penwidth](#penwidth)&nbsp;&nbsp;&nbsp; [penwidth!](#penwidth)&nbsp;&nbsp;&nbsp; [pi](#pi)&nbsp;&nbsp;&nbsp; [pos?](#pos)&nbsp;&nbsp;&nbsp; [position](#position)&nbsp;&nbsp;&nbsp; [print!](#print)&nbsp;&nbsp;&nbsp; [pu!](#pu)&nbsp;&nbsp;&nbsp; [pw!](#pw)&nbsp;&nbsp;&nbsp; [rad/deg](#rad/deg)&nbsp;&nbsp;&nbsp; [rad/turn](#rad/turn)&nbsp;&nbsp;&nbsp; [random](#random)&nbsp;&nbsp;&nbsp; [random\_int](#random\_int)&nbsp;&nbsp;&nbsp; [range](#range)&nbsp;&nbsp;&nbsp; [report!](#report)&nbsp;&nbsp;&nbsp; [rest](#rest)&nbsp;&nbsp;&nbsp; [right!](#right)&nbsp;&nbsp;&nbsp; [round](#round)&nbsp;&nbsp;&nbsp; [rt!](#rt)&nbsp;&nbsp;&nbsp; [second](#second)&nbsp;&nbsp;&nbsp; [sentence](#sentence)&nbsp;&nbsp;&nbsp; [set](#set)&nbsp;&nbsp;&nbsp; [set?](#set)&nbsp;&nbsp;&nbsp; [setheading!](#setheading)&nbsp;&nbsp;&nbsp; [show](#show)&nbsp;&nbsp;&nbsp; [showturtle!](#showturtle)&nbsp;&nbsp;&nbsp; [sin](#sin)&nbsp;&nbsp;&nbsp; [slice](#slice)&nbsp;&nbsp;&nbsp; [some](#some)&nbsp;&nbsp;&nbsp; [some?](#some)&nbsp;&nbsp;&nbsp; [split](#split)&nbsp;&nbsp;&nbsp; [sqrt](#sqrt)&nbsp;&nbsp;&nbsp; [sqrt/safe](#sqrt/safe)&nbsp;&nbsp;&nbsp; [square](#square)&nbsp;&nbsp;&nbsp; [state](#state)&nbsp;&nbsp;&nbsp; [store!](#store)&nbsp;&nbsp;&nbsp; [string](#string)&nbsp;&nbsp;&nbsp; [string?](#string)&nbsp;&nbsp;&nbsp; [strip](#strip)&nbsp;&nbsp;&nbsp; [sub](#sub)&nbsp;&nbsp;&nbsp; [sum\_of_squares](#sum\_of_squares)&nbsp;&nbsp;&nbsp; [tan](#tan)&nbsp;&nbsp;&nbsp; [tau](#tau)&nbsp;&nbsp;&nbsp; [trim](#trim)&nbsp;&nbsp;&nbsp; [tuple?](#tuple)&nbsp;&nbsp;&nbsp; [turn/deg](#turn/deg)&nbsp;&nbsp;&nbsp; [turn/rad](#turn/rad)&nbsp;&nbsp;&nbsp; [turtle\_commands](#turtle\_commands)&nbsp;&nbsp;&nbsp; [turtle\_init](#turtle\_init)&nbsp;&nbsp;&nbsp; [turtle\_state](#turtle\_state)&nbsp;&nbsp;&nbsp; [type](#type)&nbsp;&nbsp;&nbsp; [unbox](#unbox)&nbsp;&nbsp;&nbsp; [unwrap!](#unwrap)&nbsp;&nbsp;&nbsp; [unwrap\_or](#unwrap\_or)&nbsp;&nbsp;&nbsp; [upcase](#upcase)&nbsp;&nbsp;&nbsp; [update](#update)&nbsp;&nbsp;&nbsp; [update!](#update)&nbsp;&nbsp;&nbsp; [values](#values)&nbsp;&nbsp;&nbsp; [words](#words)&nbsp;&nbsp;&nbsp; [ws?](#ws)&nbsp;&nbsp;&nbsp; [zero?](#zero)
+[abs](#abs)&nbsp;&nbsp;&nbsp; [add](#add)&nbsp;&nbsp;&nbsp; [and](#and)&nbsp;&nbsp;&nbsp; [angle](#angle)&nbsp;&nbsp;&nbsp; [any?](#any)&nbsp;&nbsp;&nbsp; [append](#append)&nbsp;&nbsp;&nbsp; [assert!](#assert)&nbsp;&nbsp;&nbsp; [assoc](#assoc)&nbsp;&nbsp;&nbsp; [assoc?](#assoc)&nbsp;&nbsp;&nbsp; [at](#at)&nbsp;&nbsp;&nbsp; [atan/2](#atan2)&nbsp;&nbsp;&nbsp; [back!](#back)&nbsp;&nbsp;&nbsp; [background!](#background)&nbsp;&nbsp;&nbsp; [between?](#between)&nbsp;&nbsp;&nbsp; [bg!](#bg)&nbsp;&nbsp;&nbsp; [bk!](#bk)&nbsp;&nbsp;&nbsp; [bool](#bool)&nbsp;&nbsp;&nbsp; [bool?](#bool)&nbsp;&nbsp;&nbsp; [box?](#box)&nbsp;&nbsp;&nbsp; [butlast](#butlast)&nbsp;&nbsp;&nbsp; [ceil](#ceil)&nbsp;&nbsp;&nbsp; [chars](#chars)&nbsp;&nbsp;&nbsp; [clear!](#clear)&nbsp;&nbsp;&nbsp; [coll?](#coll)&nbsp;&nbsp;&nbsp; [colors](#colors)&nbsp;&nbsp;&nbsp; [concat](#concat)&nbsp;&nbsp;&nbsp; [contains?](#contains)&nbsp;&nbsp;&nbsp; [cos](#cos)&nbsp;&nbsp;&nbsp; [count](#count)&nbsp;&nbsp;&nbsp; [dec](#dec)&nbsp;&nbsp;&nbsp; [deg/rad](#degrad)&nbsp;&nbsp;&nbsp; [deg/turn](#degturn)&nbsp;&nbsp;&nbsp; [dict](#dict)&nbsp;&nbsp;&nbsp; [dict?](#dict)&nbsp;&nbsp;&nbsp; [diff](#diff)&nbsp;&nbsp;&nbsp; [dissoc](#dissoc)&nbsp;&nbsp;&nbsp; [dist](#dist)&nbsp;&nbsp;&nbsp; [div](#div)&nbsp;&nbsp;&nbsp; [div/0](#div0)&nbsp;&nbsp;&nbsp; [div/safe](#divsafe)&nbsp;&nbsp;&nbsp; [doc!](#doc)&nbsp;&nbsp;&nbsp; [downcase](#downcase)&nbsp;&nbsp;&nbsp; [each!](#each)&nbsp;&nbsp;&nbsp; [empty?](#empty)&nbsp;&nbsp;&nbsp; [eq?](#eq)&nbsp;&nbsp;&nbsp; [err](#err)&nbsp;&nbsp;&nbsp; [err?](#err)&nbsp;&nbsp;&nbsp; [even?](#even)&nbsp;&nbsp;&nbsp; [false?](#false)&nbsp;&nbsp;&nbsp; [fd!](#fd)&nbsp;&nbsp;&nbsp; [filter](#filter)&nbsp;&nbsp;&nbsp; [first](#first)&nbsp;&nbsp;&nbsp; [floor](#floor)&nbsp;&nbsp;&nbsp; [fn?](#fn)&nbsp;&nbsp;&nbsp; [fold](#fold)&nbsp;&nbsp;&nbsp; [forward!](#forward)&nbsp;&nbsp;&nbsp; [get](#get)&nbsp;&nbsp;&nbsp; [goto!](#goto)&nbsp;&nbsp;&nbsp; [gt?](#gt)&nbsp;&nbsp;&nbsp; [gte?](#gte)&nbsp;&nbsp;&nbsp; [heading](#heading)&nbsp;&nbsp;&nbsp; [heading/vector](#headingvector)&nbsp;&nbsp;&nbsp; [hideturtle!](#hideturtle)&nbsp;&nbsp;&nbsp; [home!](#home)&nbsp;&nbsp;&nbsp; [inc](#inc)&nbsp;&nbsp;&nbsp; [inv](#inv)&nbsp;&nbsp;&nbsp; [inv/0](#inv0)&nbsp;&nbsp;&nbsp; [inv/safe](#invsafe)&nbsp;&nbsp;&nbsp; [join](#join)&nbsp;&nbsp;&nbsp; [keep](#keep)&nbsp;&nbsp;&nbsp; [keys](#keys)&nbsp;&nbsp;&nbsp; [keyword?](#keyword)&nbsp;&nbsp;&nbsp; [last](#last)&nbsp;&nbsp;&nbsp; [left!](#left)&nbsp;&nbsp;&nbsp; [list](#list)&nbsp;&nbsp;&nbsp; [list?](#list)&nbsp;&nbsp;&nbsp; [loadstate!](#loadstate)&nbsp;&nbsp;&nbsp; [lt!](#lt)&nbsp;&nbsp;&nbsp; [lt?](#lt)&nbsp;&nbsp;&nbsp; [lte?](#lte)&nbsp;&nbsp;&nbsp; [map](#map)&nbsp;&nbsp;&nbsp; [max](#max)&nbsp;&nbsp;&nbsp; [min](#min)&nbsp;&nbsp;&nbsp; [mod](#mod)&nbsp;&nbsp;&nbsp; [mod/0](#mod0)&nbsp;&nbsp;&nbsp; [mod/safe](#modsafe)&nbsp;&nbsp;&nbsp; [mult](#mult)&nbsp;&nbsp;&nbsp; [neg](#neg)&nbsp;&nbsp;&nbsp; [neg?](#neg)&nbsp;&nbsp;&nbsp; [neq?](#neq)&nbsp;&nbsp;&nbsp; [nil?](#nil)&nbsp;&nbsp;&nbsp; [not](#not)&nbsp;&nbsp;&nbsp; [odd?](#odd)&nbsp;&nbsp;&nbsp; [ok](#ok)&nbsp;&nbsp;&nbsp; [ok?](#ok)&nbsp;&nbsp;&nbsp; [omit](#omit)&nbsp;&nbsp;&nbsp; [or](#or)&nbsp;&nbsp;&nbsp; [ordered?](#ordered)&nbsp;&nbsp;&nbsp; [pc!](#pc)&nbsp;&nbsp;&nbsp; [pd!](#pd)&nbsp;&nbsp;&nbsp; [pencolor](#pencolor)&nbsp;&nbsp;&nbsp; [pencolor!](#pencolor)&nbsp;&nbsp;&nbsp; [pendown!](#pendown)&nbsp;&nbsp;&nbsp; [pendown?](#pendown)&nbsp;&nbsp;&nbsp; [penup!](#penup)&nbsp;&nbsp;&nbsp; [penwidth](#penwidth)&nbsp;&nbsp;&nbsp; [penwidth!](#penwidth)&nbsp;&nbsp;&nbsp; [pi](#pi)&nbsp;&nbsp;&nbsp; [pos?](#pos)&nbsp;&nbsp;&nbsp; [position](#position)&nbsp;&nbsp;&nbsp; [print!](#print)&nbsp;&nbsp;&nbsp; [pu!](#pu)&nbsp;&nbsp;&nbsp; [pw!](#pw)&nbsp;&nbsp;&nbsp; [rad/deg](#raddeg)&nbsp;&nbsp;&nbsp; [rad/turn](#radturn)&nbsp;&nbsp;&nbsp; [random](#random)&nbsp;&nbsp;&nbsp; [random\_int](#random\_int)&nbsp;&nbsp;&nbsp; [range](#range)&nbsp;&nbsp;&nbsp; [report!](#report)&nbsp;&nbsp;&nbsp; [rest](#rest)&nbsp;&nbsp;&nbsp; [right!](#right)&nbsp;&nbsp;&nbsp; [round](#round)&nbsp;&nbsp;&nbsp; [rt!](#rt)&nbsp;&nbsp;&nbsp; [second](#second)&nbsp;&nbsp;&nbsp; [sentence](#sentence)&nbsp;&nbsp;&nbsp; [set](#set)&nbsp;&nbsp;&nbsp; [set?](#set)&nbsp;&nbsp;&nbsp; [setheading!](#setheading)&nbsp;&nbsp;&nbsp; [show](#show)&nbsp;&nbsp;&nbsp; [showturtle!](#showturtle)&nbsp;&nbsp;&nbsp; [sin](#sin)&nbsp;&nbsp;&nbsp; [slice](#slice)&nbsp;&nbsp;&nbsp; [some](#some)&nbsp;&nbsp;&nbsp; [some?](#some)&nbsp;&nbsp;&nbsp; [split](#split)&nbsp;&nbsp;&nbsp; [sqrt](#sqrt)&nbsp;&nbsp;&nbsp; [sqrt/safe](#sqrtsafe)&nbsp;&nbsp;&nbsp; [square](#square)&nbsp;&nbsp;&nbsp; [state](#state)&nbsp;&nbsp;&nbsp; [store!](#store)&nbsp;&nbsp;&nbsp; [string](#string)&nbsp;&nbsp;&nbsp; [string?](#string)&nbsp;&nbsp;&nbsp; [strip](#strip)&nbsp;&nbsp;&nbsp; [sub](#sub)&nbsp;&nbsp;&nbsp; [sum\_of_squares](#sum\_of_squares)&nbsp;&nbsp;&nbsp; [tan](#tan)&nbsp;&nbsp;&nbsp; [tau](#tau)&nbsp;&nbsp;&nbsp; [trim](#trim)&nbsp;&nbsp;&nbsp; [tuple?](#tuple)&nbsp;&nbsp;&nbsp; [turn/deg](#turndeg)&nbsp;&nbsp;&nbsp; [turn/rad](#turnrad)&nbsp;&nbsp;&nbsp; [turtle\_commands](#turtle\_commands)&nbsp;&nbsp;&nbsp; [turtle\_init](#turtle\_init)&nbsp;&nbsp;&nbsp; [turtle\_state](#turtle\_state)&nbsp;&nbsp;&nbsp; [type](#type)&nbsp;&nbsp;&nbsp; [unbox](#unbox)&nbsp;&nbsp;&nbsp; [unwrap!](#unwrap)&nbsp;&nbsp;&nbsp; [unwrap\_or](#unwrap\_or)&nbsp;&nbsp;&nbsp; [upcase](#upcase)&nbsp;&nbsp;&nbsp; [update](#update)&nbsp;&nbsp;&nbsp; [update!](#update)&nbsp;&nbsp;&nbsp; [values](#values)&nbsp;&nbsp;&nbsp; [words](#words)&nbsp;&nbsp;&nbsp; [ws?](#ws)&nbsp;&nbsp;&nbsp; [zero?](#zero)
 ## Function documentation
 
 ### abs