def __init__(self, min=None, max=None, message=None):
self.min = min<EOL>self.max = max<EOL>if message is not None:<EOL><INDENT>self.too_long = message<EOL>self.too_short = message<EOL>self.not_in_range = message<EOL><DEDENT>
Initialize validator
Accepts minimum and maximum length to check against. Allows only
single value to be provided.

:param min:             int or None, minimum length
:param max:             int or None, maximum length
:param message:         str, custom error message
:return:                None