Method used by the package Tropical (missing documentation) to construct a fan from Gfan output. Gfan produces more data than just rays and maximal cones and this constructor will save that data to avoid recomputation.
The object fanFromGfan is a method function.
The source of this document is in /build/reproducible-path/macaulay2-1.25.05+ds/M2/Macaulay2/packages/Polyhedra/documentation/documentation.m2:487:0.