code: def hash_for_datasource(data_source):
          
          import hashlib
          hash_value = hashlib.md5()
          hash_value.update(data_source.encode('utf-8'))
          hash_value = hash_value.hexdigest()
          return hash_value
docs: Given a data_source, return its hash.
  
          :param data_source: The data_source name from a layer.
          :type data_source: str
  
          :returns: An md5 hash for the data source name.
          :rtype: str