# $EPIC: shift_function.txt,v 1.5 2007/08/06 21:25:50 jnelson Exp $
======Synopsis:======
$__shift__(<variable name>)

======Description:======
The function takes only one argument, a variable name.  The variable is 
changed by removing its first [[what is a word|word]].  The function then
returns that first word.

======Practical:======
This function can destructively remove the first word from an [[lval]]ue 
([[ASSIGN]] variable), or non-destructively remove the first word from 
an rvalue (string of text).  This is an essential operation when you are
creating LIFOs, FIFOs, or other types of queues.

======Returns:======
The first word, which is "shifted" off of the variable, or the word list,
whichever applies.  If a variable name is provided, the variable IS CHANGED.

======Examples:======
<file>
assign foo blah booya
$shift(foo)              removes "blah" from $foo and returns "blah".
</file>