GraphExceptions.py

class NoGraph(Exception):
    def __init__(self):
        super().__init__("Graph can not be 'None'")

class NotInGraph(Exception):
    def __init__(self, item):
        super().__init__(item + " not in graph")

class NoPath(Exception):
    def __init__(self, pointA, pointB):
        super().__init__("No path exists between " + pointA + " and " + pointB)