partial fraction decomposition function for multivariate rational expressions

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Hi all:

I'd like to extend Sage's partial fraction decomposition function in the QuotientField class to a function that works on quotients of multivariate polynomials. To this end, i've found it convenient to store a rational expression $F = P/(Q_1^{e_1} \cdots Q_m^{e_m})$ as a Python list of the form [P,[Q_1,e_1],...,[Q_m,e_m]], where $Q_1,\ldots,Q_m$ are the irreducible factors of $F$'s denominator. Let's call these special kinds of lists 'widgets'. I have several auxiliary functions that manipulate widgets.

Code design questions for you. Should i make a new class for widgets, and if so, where in the Sage tree of modules should i put this class? If not, where do i put the auxiliary functions that manipulate widgets?

Thanks for your attention.

Alex