& setdiff()
 
  Syntax: setdiff(<list1>, <list2>[, <delim>])
 
  This function returns the difference of two sets -- i.e., the 
  elements in <list1> that aren't in <list2>. The list that is 
  returned is sorted. If <delim> is specified, it (rather than a 
  space) is used to separate items in the list.
 
  Example:
  > say setdiff(foo baz gleep bar, bar moof gleep)
  You say, "baz foo"
 
	See Also: setinter(), setunion(), sort()