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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 add_poly_index(self, i, j, k):
 """ Add 3 ``SCALAR`` of ``uint`` to the ``idx_data`` buffer. """

        self.idx_data.write(
            struct.pack(self.idx_fmt, i) +
            struct.pack(self.idx_fmt, j) +
            struct.pack(self.idx_fmt, k)
        )