def numeric_transformation(value)
      assert_type value, :Number, :value
      Sass::Script::Value::Number.new(
        yield(value.value), value.numerator_units, value.denominator_units)
    end
def numeric_transformation(value)
      assert_type value, :Number, :value
      Sass::Script::Value::Number.new(
        yield(value.value), value.numerator_units, value.denominator_units)
    end
This method implements the pattern of transforming a numeric value into
 another numeric value with the same units.
 It yields a number to a block to perform the operation and return a number