expression is true
	assert_exception()	assert that a command throws an exception
	assert_beeps()		assert that a command beeps
	assert_nobeep()		assert that a command does not cause a beep
	assert_fails()		assert that a command fails
	assert_report()		report a test failure

Timers:						*timer-functions*
	timer_start()		create a timer
	timer_pause()		pause or unpause a timer
	timer_stop()		stop a timer
	timer_stopall()		stop all timers
	timer_info()		get information about timers
	wait()			wait for a condition

Tags:						*tag-functions*
	taglist()		get list of matching tags
	tagfiles()		get a list of tags files
	gettagstack()		get the tag stack of a window
	settagstack()		modify the tag stack of a window

Prompt Buffer:					*promptbuffer-functions*
	prompt_getprompt()	get the effective prompt text for a buffer
	prompt_setcallback()	set prompt callback for a buffer
	prompt_setinterrupt()	set interrupt callback for a buffer
	prompt_setprompt()	set the prompt text for a buffer

Registers:					*register-functions*
	getreg()		get contents of a register
	getreginfo()		get information about a register
	getregtype()		get type of a register
	setreg()		set contents and type of a register
	reg_executing()		return the name of the register being executed
	reg_recording()		return the name of the register being recorded

Context Stack:					*ctx-functions*
	ctxget()		return context at given index from top
	ctxpop()		pop and restore top context
	ctxpush()		push given context
	ctxset()		set context at given index from top
	ctxsize()		return context stack size

Various:					*various-functions*
	mode()			get current editing mode
	visualmode()		last visual mode used
	exists()		check if a variable, function, etc. exists
	has()			check if a feature is supported in Vim
	changenr()		return number of most recent change
	did_filetype()		check if a FileType autocommand was used
	eventhandler()		check if invoked by an event handler
	getpid()		get process ID of Vim
	getscriptinfo()		get list of sourced Vim scripts
	getstacktrace()		get current stack trace of Vim scripts

	libcall()		call a function in an external library
	libcallnr()		idem, returning a number

	undofile()		get the name of the undo file
	undotree()		return the state of the undo tree for a buffer

	shiftwidth()		effective value of 'shiftwidth'

	wordcount()		get byte/word/char count of buffer

	luaeval()		evaluate |Lua| expression
	py3eval()		evaluate |Python| expression
	pyeval()		evaluate |Python| expression
	pyxeval()		evaluate |python_x| expression
	rubyeval()		evaluate |Ruby| expression

	debugbreak()		interrupt a program being debugged

==============================================================================
*41.7*	Defining a function

Vim enables you to define your own functions.  The basic function declaration
begins as follows: >

	:function {name}({var1}, {var2}, ...)
	:  {body}
	:endfunction
<
	Note:
	Function names must begin with a capital letter.

Let's define a short function to return the smaller of two numbers.  It starts
with this line: >

	:function Min(num1, num2)

This tells Vim that the function is named "Min" and it takes two arguments:
"num1" and "num2".
   The first thing you need to do is to check to see which number is smaller:
   >
	:  if a:num1 < a:num2

The special prefix "a:" tells Vim that the variable is a function argument.
Let's assign the variable "smaller" the value of the smallest number: >

	:  if a:num1 < a:num2
	:    let smaller = a:num1
	:  else
	:    let smaller = a:num2
	:  endif

The variable "smaller" is a local variable.  Variables used inside a function
are local unless prefixed by something like "g:", "a:", or "s:".

	Note:
	To access a global variable from inside a function you must prepend
	"g:" to it.  Thus "g:today" inside a function is used for the global
	variable "today", and "today" is another variable, local to the
	function.

You now use the ":return" statement to return the smallest number to the user.
Finally, you end the function: