Create an Evidence instance from the given mapping

        :param evidence_mapping: a mapping (e.g. dict) of values provided by Watson
        :return: a new Evidence

def from_mapping(cls, evidence_mapping):
        """Create an Evidence instance from the given mapping

        :param evidence_mapping: a mapping (e.g. dict) of values provided by Watson
        :return: a new Evidence
        """
        return cls(metadata_map=MetadataMap.from_mapping(evidence_mapping['metadataMap']),
                   copyright=evidence_mapping['copyright'],
                   id=evidence_mapping['id'],
                   terms_of_use=evidence_mapping['termsOfUse'],
                   document=evidence_mapping['document'],
                   title=evidence_mapping['title'],
                   text=evidence_mapping['text'],
                   value=evidence_mapping['value'])