'Construct a Filter matching values containing ``substring``.
Parameters
substring : str
Sub-string against which to compare values produced by ``self``.
Returns
matches : Filter
Filter returning True for all sid/date pairs for which ``self``
produces a string containing ``substring``.'

@string_classifiers_only
@expect_types(substring=(bytes, unicode))
def has_substring(self, substring):

    return ArrayPredicate(term=self, op=LabelArray.has_substring, opargs=(substring,))
