Return a copy of self.

        This function does not make use of the context.  The result has the
        same precision as the original.

def copy(self):
        """ Return a copy of self.

        This function does not make use of the context.  The result has the
        same precision as the original.

        """
        result = mpfr.Mpfr_t.__new__(BigFloat)
        mpfr.mpfr_init2(result, self.precision)
        mpfr.mpfr_set(result, self, ROUND_TIES_TO_EVEN)
        return result