code: def get_all_dbparameter_groups(self, groupname=None, max_records=None,
                                    marker=None):
          
          params = {}
          if groupname:
              params['DBParameterGroupName'] = groupname
          if max_records:
              params['MaxRecords'] = max_records
          if marker:
              params['Marker'] = marker
          return self.get_list('DescribeDBParameterGroups', params,
                               [('DBParameterGroup', ParameterGroup)])
docs: Get all parameter groups associated with your account in a region.
  
          :type groupname: str
          :param groupname: The name of the DBParameter group to retrieve.
                            If not provided, all DBParameter groups will be returned.
  
          :type max_records: int
          :param max_records: The maximum number of records to be returned.
                              If more results are available, a MoreToken will
                              be returned in the response that can be used to
                              retrieve additional records.  Default is 100.
  
          :type marker: str
          :param marker: The marker provided by a previous request.
  
          :rtype: list
          :return: A list of :class:`boto.ec2.parametergroup.ParameterGroup`