'Remove a node from the sort input'

def remove(self, name):

    self.names.remove(name)
    del self.name2val[name]
    after = self.name2after.pop(name, [])
    if after:
        self.req_after.remove(name)
        for u in after:
            self.order.remove((u, name))
    before = self.name2before.pop(name, [])
    if before:
        self.req_before.remove(name)
        for u in before:
            self.order.remove((name, u))
