code: def dump(self, force=False):
          
  
          if force:
              self._set_contents(force=force)
  
          if self._fields and self.children is not None:
              for index, (field_name, _, params) in enumerate(self._fields):
                  if self.children[index] is not VOID:
                      continue
                  if 'default' in params or 'optional' in params:
                      continue
                  raise ValueError(unwrap(
                      '''
                      Field "%s" is missing from structure
                      ''',
                      field_name
                  ))
  
          return Asn1Value.dump(self)
docs: Encodes the value using DER
  
          :param force:
              If the encoded contents already exist, clear them and regenerate
              to ensure they are in DER format instead of BER format
  
          :return:
              A byte string of the DER-encoded value