OPTIONAL
SYNOPSIS
	string process_string(string str)

DESCRIPTION
	Searches string str for occurences of a "value by function
	call", which is @@ followed by an implicit function call. See
	"value_by_function_call" in the principles section.
	
	The value should contain a string like this:
	@@function[:filename][|arg|arg]@@
	
	function must return a string or else the string which should be
	processed will be returned unchanged.
	
	Note that process_string() does not recurse over returned
	replacement values. If a function returns another function
	description, that description will not be replaced.

	Note that both filename and args are optional.

EXAMPLE
	string foo(string str) {
	   return "ab"+str+"ef";
	}
	void func() {
	   write(process_string("@@foo|cd@@")+"\n");
	}
	
	The function func() will print out the string "abcdef".

BUGS
	Using process_string() can lead to severe security problems.

HISTORY
	Because of the security problems, process_string() is an
	optional efun since 3.2.1@34

SEE ALSO
	notify_fail(E), closures(LPC), get_bb_uid(M)
