======Synopsis:======
__unshift__ <variable name> <word> \\
__shift__   <variable name>

======Description:======
__UNSHIFT__ prepends the given word (or words) to the given variable,
padded with a single space.  The variable name itself may not contain
a leading '$'; the command uses the variable itself, not the expanded
contents.  If the variable does not exist, it is created containing
the given word(s) (just as if [[ASSIGN]] were used).

======Aliases:======
__SHIFT__ is the exact opposite of __UNSHIFT__, in that it chops off the first
word in the variable.  If there is only one word in the variable, the variable
is deleted.  Both __UNSHIFT__ and __SHIFT__ are functionally equivalent to the
$[[unshift function|unshift]]() and $[[shift function|shift]]() functions,
respectively.