Adding in evolution repository and service interfaces with basic initial implementation
Using TDD gradually building up the evolution service to verify if a given monster can evolve.
Using TDD gradually building up the evolution service to verify if a given monster can evolve.  Now adding in the idea of requirements for evolving.
updating doc block
Adding more unit tests for evolution service can evolve question.  Also refactoring the function to be cleaner.
Refactoring code to be cleaner