@classmethod
def pairs(cls, fields, order_by=None, _result=None):
    """
            Returns a list of two element tuples.
            [
                (1, 'apple')
                (2, 'banana')
            ]

            fields: string with the name of the fields you want to pair with
                a ":" seperating them.  I.e.:

                Fruit.pairs('id:name')

            order_by = order_by clause or iterable of order_by clauses
        """
    key_field_name, value_field_name = fields.split(':')
    if _result is None:
        _result = cls.list(order_by)
    retval = []
    for obj in _result:
        retval.append((getattr(obj, key_field_name), getattr(obj,
            value_field_name)))
    return retval
