Manage the multiplication (and division) between two value wrapped in the same metric-system

[xvw]

Actually, Mizur could not proceed "non-linear" operation, ie: 1cm * 2cm.

     @doc """
      Multiplies a `typed_value` by a `number`. The subtype of the return value 
      will be the subtype of the left `typed_value`.
      """
      @spec times(t, number) :: t 
      def times(a, b) when is_number(b) do 
        x = unwrap(a)
        %{ a | value: (x * b)}
end

Actually, you can do 1cm * x and not 1cm * 2cm (because x.cm * y.cm should equals x*y cm2.
The goal of this issue is to manage a "base notion" and preserve the coercion function.

Good Luck