docs: def retrieve(self, id) :
          """
          Retrieve a single source
  
          Returns a single source available to the user by the provided id
          If a source with the supplied unique identifier does not exist it returns an error
  
          :calls: ``get /lead_sources/{id}``
          :param int id: Unique identifier of a LeadSource.
          :return: Dictionary that support attriubte-style access and represent LeadSource resource.
          :rtype: dict
          """
  
          _, _, lead_source = self.http_client.get("/lead_sources/{id}".format(id=id))
          return lead_source