is_nonnegative_integer

mathtools.is_nonnegative_integer(expr)

Is true when expr equals a nonnegative integer.

>>> mathtools.is_nonnegative_integer(99)
True
>>> mathtools.is_nonnegative_integer(0)
True

Otherwise false:

>>> mathtools.is_nonnegative_integer(-1)
False

Returns true or false.