function KEYWORD_DEFINED, Key

;+
; NAME:
;	KEYWORD_DEFINED
;
; PURPOSE:
;	This function returns 1 if Key is defined, 0 if not.  It is
;	often called in conditionals.  Note that this is distinct from
;	the keyword_set() routine in IDL.  In IDL, a keyword can be
;	defined and not have a value assigned.
;
; CATEGORY:
;	Comet Nucleus Tour CRISP IR Spectrometer calibration pipeline.
;
; CALLING SEQUENCE:
;
;	print, KEYWORD_DEFINED(Key)
;
; INPUTS:
;	Key:	The key whose definedness to test.
;
; OUTPUTS:
;	This function returns 1 if Key is defined, 0 if not.
;
; EXAMPLE:
;
;	Define an image mask if one is not defined already.  Note that
;	a mask value of [0] is legal, and would fail the keyword_set()
;	test.
;
;	if keyword_defined(mask) then begin
;		...
;	else
;		mask = [1]
;	endif
;
; MODIFICATION HISTORY:
; 	Written by:	Joseph Harrington, Cornell. 1996 February 13
;			jh@oobleck.astro.cornell.edu
;-

if n_elements(key) eq 0 then return, 0 else return, 1

end