'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`'

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)])
