'Returns the detailed parameter list for a particular DB
parameter group.
:type db_parameter_group_name: string
:param db_parameter_group_name:
The name of a specific DB parameter group to return details for.
Constraints:
+ Must be 1 to 255 alphanumeric characters
+ First character must be a letter
+ Cannot end with a hyphen or contain two consecutive hyphens
:type source: string
:param source: The parameter types to return.
Default: All parameter types returned
Valid Values: `user | system | engine-default`
:type max_records: integer
:param max_records: The maximum number of records to include in the
response. If more records exist than the specified `MaxRecords`
value, a pagination token called a marker is included in the
response so that the remaining results may be retrieved.
Default: 100
Constraints: minimum 20, maximum 100
:type marker: string
:param marker: An optional pagination token provided by a previous
`DescribeDBParameters` request. If this parameter is specified, the
response includes only records beyond the marker, up to the value
specified by `MaxRecords`.'

def describe_db_parameters(self, db_parameter_group_name, source=None, max_records=None, marker=None):

    params = {'DBParameterGroupName': db_parameter_group_name}
    if (source is not None):
        params['Source'] = source
    if (max_records is not None):
        params['MaxRecords'] = max_records
    if (marker is not None):
        params['Marker'] = marker
    return self._make_request(action='DescribeDBParameters', verb='POST', path='/', params=params)
