def validate(self, value, model=None, context=None):
if not isinstance(value, Iterable):<EOL><INDENT>return Error(self.not_iterable)<EOL><DEDENT>try:<EOL><INDENT>next(iter(value))<EOL><DEDENT>except StopIteration:<EOL><INDENT>return Error(self.cant_be_empty)<EOL><DEDENT>return Error()<EOL>
Validate
Perform value validation and return result

:param value:           value to check
:param model:           parent model being validated
:param context:         object or None, validation context
:return:                shiftschema.results.Error