code: def _parse_corporations(self, datafield, subfield, roles=["any"]):
          
          if len(datafield) != 3:
              raise ValueError(
                  "datafield parameter have to be exactly 3 chars long!"
              )
          if len(subfield) != 1:
              raise ValueError(
                  "Bad subfield specification - subield have to be 3 chars long!"
              )
          parsed_corporations = []
          for corporation in self.get_subfields(datafield, subfield):
              other_subfields = corporation.other_subfields
  
              # check if corporation have at least one of the roles specified in
              # 'roles' parameter of function
              if "4" in other_subfields and roles != ["any"]:
                  corp_roles = other_subfields["4"]  # list of role parameters
  
                  relevant = any(map(lambda role: role in roles, corp_roles))
  
                  # skip non-relevant corporations
                  if not relevant:
                      continue
  
              name = ""
              place = ""
              date = ""
  
              name = corporation
  
              if "c" in other_subfields:
                  place = ",".join(other_subfields["c"])
              if "d" in other_subfields:
                  date = ",".join(other_subfields["d"])
  
              parsed_corporations.append(Corporation(name, place, date))
  
          return parsed_corporations
docs: Parse informations about corporations from given field identified
          by `datafield` parameter.
  
          Args:
              datafield (str): MARC field ID ("``110``", "``610``", etc..)
              subfield (str):  MARC subfield ID with name, which is typically
                               stored in "``a``" subfield.
              roles (str): specify which roles you need. Set to ``["any"]`` for
                           any role, ``["dst"]`` for distributors, etc.. For
                           details, see
                           http://www.loc.gov/marc/relators/relaterm.html
  
          Returns:
              list: :class:`Corporation` objects.