I can't speak for OP, but GOF (Gang of Four) is a reference to the four authors of a classic Design Patterns text. [1] This repo appears to be Python examples of some of the patterns referenced in the original text.
[1]: Design Patterns: Elements of Reusable Object-Oriented Software by Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides
[1]: Design Patterns: Elements of Reusable Object-Oriented Software by Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides