(self, fns)
:param fns: a dictionary mapping names to functions that return a
            query.
:param fns: a dictionary mapping names to functions that return a
            query.
: param fns : a dictionary mapping names to functions that return a query .
def __init__(self, fns):
        """
        :param fns: a dictionary mapping names to functions that return a
            query.
        """

        self.fns = fns
def __init__ ( self , fns ) : self . fns = fns