(texinfo) Sample Function Definition

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 A Sample Function Definition
 ============================
 
   A function definition uses the `@defun' and `@end defun' commands.
 The name of the function follows immediately after the `@defun' command
 and it is followed, on the same line, by the parameter list.
 
   Here is a definition from  Calling Functions (elisp)Calling
 Functions.
 
       - Function: apply function &rest arguments
           `apply' calls FUNCTION with ARGUMENTS, just like `funcall'
           but with one difference: the last of ARGUMENTS is a list of
           arguments to give to FUNCTION, rather than a single argument.
           We also say that this list is "appended" to the other
           arguments.
 
           `apply' returns the result of calling FUNCTION.  As with
           `funcall', FUNCTION must either be a Lisp function or a
           primitive function; special forms and macros do not make
           sense in `apply'.
 
                (setq f 'list)
                     => list
                (apply f 'x 'y 'z)
                error--> Wrong type argument: listp, z
                (apply '+ 1 2 '(3 4))
                     => 10
                (apply '+ '(1 2 3 4))
                     => 10
                
                (apply 'append '((a b c) nil (x y z) nil))
                     => (a b c x y z)
 
           An interesting example of using `apply' is found in the
           description of `mapcar'.
 
   In the Texinfo source file, this example looks like this:
 
      @defun apply function &rest arguments
      @code{apply} calls @var{function} with
      @var{arguments}, just like @code{funcall} but with one
      difference: the last of @var{arguments} is a list of
      arguments to give to @var{function}, rather than a single
      argument.  We also say that this list is @dfn{appended}
      to the other arguments.
      
      @code{apply} returns the result of calling
      @var{function}.  As with @code{funcall},
      @var{function} must either be a Lisp function or a
      primitive function; special forms and macros do not make
      sense in @code{apply}.
      
      @example
      (setq f 'list)
           @result{} list
      (apply f 'x 'y 'z)
      @error{} Wrong type argument: listp, z
      (apply '+ 1 2 '(3 4))
           @result{} 10
      (apply '+ '(1 2 3 4))
           @result{} 10
      
      (apply 'append '((a b c) nil (x y z) nil))
           @result{} (a b c x y z)
      @end example
      
      An interesting example of using @code{apply} is found
      in the description of @code{mapcar}.
      @end defun
 
 In this manual, this function is listed in the Command and Variable
 Index under `apply'.
 
   Ordinary variables and user options are described using a format like
 that for functions except that variables do not take arguments.
 

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