Implement multiparameter overloaded functions, with explicit registration

[nthiery]

CC: @sagetrac-sage-combinat

Component: coercion

Keywords: overloading

Author: Nicolas M. Thiéry

Issue created by migration from https://trac.sagemath.org/ticket/8900

[kevindilks]

comment:1

I noticed that this ticket was mentioned in hopf_algebras.py in a commented out TODO note for antipode_by_coercion, and it seemed like it would be used to do what ticket: 15573 is attempting to achieve (have product/coproduct/antipode for Hopf algebras automatically choose a realization where the corresponding method is defined). Did this ever make it into Sage, and if not, are there still any plans to put it in?