   IsSimple(g)

Currently, this function is a placeholder and should not be used.
If implemented, its behavior will be as described in the next paragraph.

Returns 1 if the geometry value g has no anomalous geometric points,
such as self-intersection or self-tangency. IsSimple() returns 0 if the
argument is not simple, and -1 if it is NULL.

The description of each instantiable geometric class given earlier in
the chapter includes the specific conditions that cause an instance of
that class to be classified as not simple.
