circuitbuilder: add comment about future refactor

        self.built_circuits.clear()

# In a future refactor, remove this class, since sbws chooses the relays to

# build the circuit, the relays are not just choosen as random as this class

# does.

class GapsCircuitBuilder(CircuitBuilder):

    ''' The build_circuit member function takes a list. Falsey values in the

    list will be replaced with relays chosen uniformally at random; Truthy