code: def get_corporations(self, roles=["dst"]):
          
          corporations = self._parse_corporations("110", "a", roles)
          corporations += self._parse_corporations("610", "a", roles)
          corporations += self._parse_corporations("710", "a", roles)
          corporations += self._parse_corporations("810", "a", roles)
  
          return corporations
docs: Args:
              roles (list, optional): Specify which types of corporations you
                    need. Set to ``["any"]`` for any role, ``["dst"]`` for
                    distributors, etc..
  
          Note:
              See http://www.loc.gov/marc/relators/relaterm.html for details.
  
          Returns:
              list: :class:`.Corporation` objects specified by roles parameter.