code: def copysign(x, y, context=None):
      
      return _apply_function_in_current_context(
          BigFloat,
          mpfr.mpfr_copysign,
          (
              BigFloat._implicit_convert(x),
              BigFloat._implicit_convert(y),
          ),
          context,
      )
docs: Return a new BigFloat object with the magnitude of x but the sign of y.