The purpose of this package is to provide extra capabilities not found in the
core Chebfun classes and functions. To be added to this folder, a function must
have the following properties:

1. No other functions depend on it.

2. It depends only on built-in MATLAB and core Chebfun.

3. It is well documented, following MATLAB conventions for the help
   documentation block. In particular, it should provide at least one example
   of usage that will be printed out by MATLAB help.

4. It has a comment with the author's name and email, and the month and year
   of original authorship.

5. It has a notice assigning copyright to The University of Oxford and The
   Chebfun Developers.