 able to convert the type of the index (A dynamic Python type)

        to the actual type that the C++ container expects.

      </p>

      <p>

        When a container expands or contracts, held indexes to its elements

        must be adjusted to follow the movement of data. For instance, if we

        erase 3 elements, starting from index 0 from a 5 element vector, what

        used to be at index 4 will now be at index 1:

      </p>

      <pre>

    [a][b][c][d][e] ---&gt; [d][e]

    