def from_epsg(cls, code):
        """
        Given an integer code, returns an EPSG-like mapping.
        Note: the input code is not validated against an EPSG database.
        """
        if int(code) <= 0:
            raise ValueError("EPSG codes are positive integers")
        return cls({'init': "epsg:{}".format(code), 'no_defs': True})