non-zero
			The support for a following command was added in Vim
			8.0.0654, before that any argument was silently
			ignored.

			To be able to define a function inside an `:execute`
			command, use line breaks instead of |:bar|: >
				:exe "func Foo()\necho 'foo'\nendfunc"
<
				*:delf* *:delfunction* *E131* *E933*
:delf[unction][!] {name}
			Delete function {name}.
			{name} can also be a |Dictionary| entry that is a
			|Funcref|: >
				:delfunc dict.init
<			This will remove the "init" entry from "dict".  The
			function is deleted if there are no more references to
			it.
			With the ! there is no error if the function does not
			exist.
							*:retu* *:return* *E133*
:retu[rn] [expr]	Return from a function.  When "[expr]" is given, it is
			evaluated and returned as the result of the function.
			If "[expr]" is not given, the number 0 is returned.
			When a function ends without an explicit ":return",
			the number 0 is returned.
			Note that there is no check for unreachable lines,
			thus there is no warning if commands follow ":return".
			Also, there is no check if the following
			line contains a valid command.  Forgetting the line
			continuation backslash may go unnoticed: >
				return 'some text'
				       .. ' some more text'
<			Will happily return "some text" without an error.  It
			should have been: >
				return 'some text'
				       \ .. ' some more text'
<
			If the ":return" is used after a |:try| but before the
			matching |:finally| (if present), the commands
			following the ":finally" up to the matching |:endtry|
			are executed first.  This process applies to all
			nested ":try"s inside the function.  The function
			returns at the outermost ":endtry".

						*function-argument* *a:var*
An argument can be defined by giving its name.  In the function this can then
be used as "a:name" ("a:" for argument).
					*a:0* *a:1* *a:000* *E740* *...*
Up to 20 arguments can be given, separated by commas.  After the named
arguments an argument "..." can be specified, which means that more arguments
may optionally be following.  In the function the extra arguments can be used
as "a:1", "a:2", etc.  "a:0" is set to the number of extra arguments (which
can be 0).  "a:000" is set to a |List| that contains these arguments.  Note
that "a:1" is the same as "a:000[0]".
								*E742*
The a: scope and the variables in it cannot be changed, they are fixed.
However, if a composite type is used, such as |List| or |Dictionary| , you can
change their contents.  Thus you can pass a |List| to a function and have the
function add an item to it.  If you want to make sure the function cannot
change a |List| or |Dictionary| use |:lockvar|.

It is also possible to define a function without any arguments.  You must
still supply the () then.

It is allowed to define another function inside a function body.

						*optional-function-argument*
You can provide default values for positional named arguments.  This makes
them optional for function calls.  When a positional argument is not
specified at a call, the default expression is used to initialize it.
This only works for functions declared with `:function`, not for
lambda expressions |expr-lambda|.

Example: >
  function Something(key, value = 10)
     echo a:key .. ": " .. a:value
  endfunction
  call Something('empty')	"empty: 10"
  call Something('key', 20)	"key: 20"

The argument default expressions are evaluated at the time of the function
call, not when the function is defined.  Thus it is possible to use an
expression which is invalid the moment the function is defined.  The
expressions are also only evaluated when arguments are not specified during a
call.

								*E989*
Optional arguments with default expressions must occur after any mandatory
arguments.  You can use "..." after all optional named arguments.

It is possible for later argument defaults to refer to prior arguments,
but not the other way around.  They must be prefixed with "a:", as with all
arguments.

Example