xtual representation of the date (<code class="literal">str</code>). The textual
        representation is expected to match the format mask. However you do not
        need to have a 1:1 mapping of the string to the format mask. The
        function only analyzes the sequential order and looks for the literals
        <code class="literal">yy</code> or <code class="literal">yyyy</code> that indicate the
        position of the year, <code class="literal">mm</code> to indicate the position of
        the mo