PYTHON MUTATION. Python is a mutation which has the resemblance of a python snake. It creates a darker (black) layer over the horse's base coat created the pattern of a python on the horse's coat. The marking may be diluted based on how light the horse's coat is. A white horse will have a creamy color instead of black. This mutation generally covers the entire body but can be shown with as much black as desired. This mutation does not affect the horse's mane/tail.