pybel.tokens.parse_result_to_dsl doesn't capture 'concept' information

[amanchoudhri]

Current behavior

When passing a pybel Entity to parse_result_to_dsl(), the 'concept' entries don't get mapped to a corresponding 'entity' parameter in the returned node. For example, when passing {'function': 'Complex', 'members': [{}, {}], 'concept': {'namespace': 'hgnc', 'name': 'ca'}} to the function, the BEL complex returned has an entity value of None, as shown in the following image.

Expected behavior

Expected the function to return an entity value consistent with the node schema defined in the schema sub-module.