def *(other)
      if other.is_a?(Value)
        other = other.to_f
      end
      if other.is_a?(Numeric)
        to_f * other
      else
        raise "Unexpected argument (#{other.inspect})"
      end
    end
def *(other)
      if other.is_a?(Value)
        other = other.to_f
      end
      if other.is_a?(Numeric)
        to_f * other
      else
        raise "Unexpected argument (#{other.inspect})"
      end
    end
Multiply a Value object.

 @param other [Numeric, Value] Multiplier.

 @return [Numeric] Result of multiplication.