PRO wlog, file, str, OVERWRITE = overwrite

; Description: This module simply appends the string "str" to the text file
;              specified by "file", creating the file if it does not exist
;              already. The user may specify to overwrite the file if it 
;              already exists.
;
; Input Parameters:
;
;   file - STRING - The full directory path and file name of the file to be 
;                   written to.
;   str - STRING - The text string to be appended to "file". If "str" is not
;                  a scalar string, then this module does nothing.
;
; Keywords:
;
;   If the keyword OVERWRITE is set (as "/OVERWRITE"), then the module will 
;   remove the file if it already exists, and then it will recreate the file
;   with the required string on the first line.
;
; Author: Dan Bramich (dan.bramich@hotmail.co.uk)
;
; History:
;
;   19/04/2008 - Module created (dmb)

;If "str" is not a scalar string, then do nothing

;Test for the existence of the file

;If the file does not exist

  ;Create the file containing the required text

;If the file already exists

  ;If the keyword OVERWRITE is set

    ;Remove the file before recreating it with the required string on the first line

  ;If the keyword OVERWRITE is not set

    ;Append the required text to the file