def _normalize(self, key, value):
<EOL>if value is None:<EOL><INDENT>return None<EOL><DEDENT>normalize_func = getattr(self, '<STR_LIT>'.format(key),<EOL>lambda x: x)<EOL>return normalize_func(value)<EOL>
Use normalize_<key> methods to normalize user input. Any user
input will be normalized at the moment it is used as filter,
or entered as a value of Task attribute.