sage

cf43e358 - gh-35780: Reduce dependency to rainbow in sage.graphs.graph_coloring

gh-35780: Reduce dependency to rainbow in sage.graphs.graph_coloring We add a method to format colorings to reduce the number of places in which method rainbow from `sage.plot.colors` is called in `sage.graphs.graph_coloring`. This is a first step toward the resolution of #35777 ### :memo: Checklist - [x] The title is concise, informative, and self-explanatory. - [x] The description explains in detail what this PR is about. - [x] I have linked a relevant issue or discussion. - [x] I have created tests covering the changes. - [x] I have updated the documentation accordingly. URL: https://github.com/sagemath/sage/pull/35780 Reported by: David Coudert Reviewer(s): Matthias Köppe