======Synopsis:======
__push__ <variable name> <word> \\
__pop__  <variable name>

======Description:======
__PUSH__ appends the given word 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).

Just as with the [[push]] function, if [[xdebug]] dword is turned on, then
<word> is treated as **one word** and it will be double quoted by the client
before it is appended to the variable.  If [[xdebug]] dword is turned off,
then you get the epic4 behavior.

======Aliases:======
__POP__ is the exact opposite of __PUSH__, in that it pops off the last word
in the variable.  If there is only one word in the variable, the
variable is deleted.  Both __PUSH__ and __POP__ are functionally equivalent
to the $[[push function|push]]() and $[[pop function|pop]]() functions, respectively.