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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 tot_edges(self):
 """ Returns the number of edges in the convex hull. Useful for identifying catalytically active sites. """

        all_edges = []
        for facet in self.facets:
            edges = []
            pt = self.get_line_in_facet(facet)

            lines = []
            for i, p in enumerate(pt):
                if i == len(pt) / 2:
                    break
                lines.append(tuple(sorted(tuple([tuple(pt[i*2]), tuple(pt[i*2+1])]))))

            for i, p in enumerate(lines):
                if p not in all_edges:
                    edges.append(p)

            all_edges.extend(edges)

        return len(all_edges)