'Return True if a given embedded doc matches all the filter
kwargs. If it doesn\'t return False.'

@classmethod
def __match_all(cls, embedded_doc, kwargs):

    for (key, expected_value) in kwargs.items():
        doc_val = getattr(embedded_doc, key)
        if ((doc_val != expected_value) and (six.text_type(doc_val) != expected_value)):
            return False
    return True
