Maxima Function
askinteger (expr, integer)
askinteger(expr)
askinteger(expr,even)
askinteger(expr,odd)
askinteger (expr, integer) attempts to determine from the assume database
whether expr is an integer.
askinteger prompts the user if it cannot tell otherwise,
and attempt to install the information in the database if possible.
askinteger (expr) is equivalent to askinteger (expr, integer).
askinteger (expr, even) and askinteger (expr, odd)
likewise attempt to determine if expr is an even integer or odd integer, respectively.