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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 get_top_edge_depth(self):
 """ Return minimum depth of surface's top edge. :returns: Float value, the vertical distance between the earth surface and the shallowest point in surface's top edge in km. """

        top_edge = self.mesh[0:1]
        if top_edge.depths is None:
            return 0
        else:
            return numpy.min(top_edge.depths)