e
    <code>int - T</code> and does not provide <code>T operator-(int, const
    T&amp;)</code>, the compiler will consider <code>double operator-(double,
    const T&amp;)</code> to be a better match than <code>T operator-(const
    T&amp;, const T&amp;)</code>, which will probably be different from the
    user's intention. To define a complete set of operator signatures,
    additional 'left' forms of the two-argument template forms are provided
    (<code><a href="#subtractable2_left">subtractable2_left