def children(self, node):
        """find the children of a given node"""
        c = []
        p = self.rev(node)
        for r in range(p + 1, len(self)):
            prevs = [pr for pr in self.parentrevs(r) if pr != nullrev]
            if prevs:
                for pr in prevs:
                    if pr == p:
                        c.append(self.node(r))
            elif p == nullrev:
                c.append(self.node(r))
        return c