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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 _arc(self, prom, sig):
 """ Computes the in-zodiaco and in-mundo arcs between a promissor and a significator. """

        arcm = arc(prom['ra'], prom['decl'], 
                   sig['ra'], sig['decl'], 
                   self.mcRA, self.lat)
        arcz = arc(prom['raZ'], prom['declZ'], 
                   sig['raZ'], sig['declZ'], 
                   self.mcRA, self.lat)
        return {
            'arcm': arcm,
            'arcz': arcz
        }