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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def cross_goal(state):
 """ The goal function for cross solving search. """

        centres, edges = state
        for edge in edges:
            if "D" not in edge.facings:
                return False
            if edge["D"] != centres["D"]["D"]:
                return False
            k = "".join(edge.facings.keys()).replace("D", "")
            if edge[k] != centres[k][k]:
                return False
        return True