ismethod() work-around for 5.x

It appears that in Octave 5.x and earlier the ismethod() function does not find methods defined in a classdef. My current workaround is to move the methods into separate files in their own @class_name directory, but I’d rather not. So I was hoping to include my own ismethod() functionality in my package to support Octave 5.x.

I would just look at the ismethod() source in Octave 6.x except that my code needs to be distributed under a BSD license.

So, can anyone suggest an efficient approach for detecting whether a name is a method of an object … one that I could implement and include in my BSD licensed project?

Thanks,

    Ray