Beware that evaluating an index may
					cause an error message for an invalid
					expression.  E.g.: >vim
					   let l = [1, 2, 3]
					   echo exists("l[5]")
<					   0 >vim
					   echo exists("l[xx]")
<					   E121: Undefined variable: xx
					   0
			&option-name	Vim option (only checks if it exists,
					not if it really works)
			+option-name	Vim option that works.
			$ENVNAME	environment variable (could also be
					done by comparing with an empty
					string)
			`*funcname`	built-in function (see |functions|)
					or user defined function (see
					|user-function|). Also works for a
					variable that is a Funcref.
			:cmdname	Ex command: built-in command, user
					command or command modifier |:command|.
					Returns:
					1  for match with start of a command
					2  full match with a command
					3  matches several user commands
					To check for a supported command
					always check the return value to be 2.
			:2match		The |:2match| command.
			:3match		The |:3match| command (but you
					probably should not use it, it is
					reserved for internal usage)
			#event		autocommand defined for this event
			#event#pattern	autocommand defined for this event and
					pattern (the pattern is taken
					literally and compared to the
					autocommand patterns character by
					character)
			#group		autocommand group exists
			#group#event	autocommand defined for this group and
					event.
			#group#event#pattern
					autocommand defined for this group,
					event and pattern.
			##event		autocommand for this event is
					supported.

		Examples: >vim
			echo exists("&mouse")
			echo exists("$HOSTNAME")
			echo exists("*strftime")
			echo exists("*s:MyFunc")
			echo exists("*MyFunc")
			echo exists("*v:lua.Func")
			echo exists("bufcount")
			echo exists(":Make")
			echo exists("#CursorHold")
			echo exists("#BufReadPre#*.gz")
			echo exists("#filetypeindent")
			echo exists("#filetypeindent#FileType")
			echo exists("#filetypeindent#FileType#*")
			echo exists("##ColorScheme")
<		There must be no space between the symbol (&/$/*/#) and the
		name.
		There must be no extra characters after the name, although in
		a few cases this is ignored.  That may become stricter in the
		future, thus don't count on it!
		Working example: >vim
			echo exists(":make")
<		NOT working example: >vim
			echo exists(":make install")

<		Note that the argument must be a string, not the name of the
		variable itself.  For example: >vim
			echo exists(bufcount)
<		This doesn't check for existence of the "bufcount" variable,
		but gets the value of "bufcount", and checks if that exists.

                Parameters: ~
                  • {expr} (`string`)

                Return: ~
                  (`0|1`)

exp({expr})                                                              *exp()*
		Return the exponential of {expr} as a |Float| in the range
		[0, inf].
		{expr} must evaluate to a |Float| or a |Number|.
		Returns 0.0 if {expr} is not a |Float| or a |Number|.
		Examples: >vim
			echo exp(2)
<			7.389056 >vim
			echo exp(-1)
<			0.367879

                Parameters: ~
                  • {expr} (`number`)

                Return: ~
                  (`any`)

expand({string} [, {nosuf} [, {list}]])                               *expand()*
		Expand wildcards and the following special keywords in
		{string}.  'wildignorecase' applies.

		If {list} is given and it is |TRUE|, a List will be returned.
		Otherwise the result is a String and when there are several
		matches, they are separated by <NL> characters.

		If the expansion fails, the result is an empty string.  A name
		for a non-existing file is not included, unless {string} does
		not start with '%', '#' or '<', see below.

		When {string} starts with '%', '#' or '<', the expansion is
		done like for the |cmdline-special| variables with their
		associated modifiers.  Here is a short overview:

			%		current file name
			#		alternate file name
			#n		alternate file name n
			<cfile>		file