def __init__(self, allow_false=False, allow_zero=False, message=None):
self.allow_false = allow_false<EOL>self.allow_zero = allow_zero<EOL>if message is not None:<EOL><INDENT>self.value_required = message<EOL><DEDENT>
Initialize validator
Accepts an optional custom error message.

:param allow_false      bool, whether to allow False as value
:param allow_zero:      bool, whether to allow 0 as value
:param message:         str, custom error message
:return:                None