"next()" method dispatcher is called.
This approach should get rid of the problem with circular reference which
causes the text_input instance not be erasable because of strong reference
to `self' in `self.next.im_self'.
Later a writing facility can be added as well.
* Note that this module is intended only for reading/writing
Fortran-generated files.
It is not recommended for any other purpose because of its terrible feature:
no metadata, no description whatsoever.
wirawan