This rule applies whenever an ``if`` statement is followed by one or more ``elsif`` statements; the final ``elsif`` should be followed by an ``else`` statement.
The requirement for a final ``else`` statement is defensive programming.
The ``else`` statement should either take appropriate action or contain a suitable comment as to why no action is taken. This is consistent with the requirement to have a final ``else`` clause in a ``case`` statement.
When all branches of an ``if``-``else if`` end with ``return``, ``break`` or ``throw``, the code that comes after the ``if`` implicitly behaves as if it was in an ``else`` clause. This rule will therefore ignore that case.
