| 45 | |
| 46 | |
| 47 | class KeyNotFoundError(Exception): |
| 48 | def __init__(self, cause, keys=None, visited=None): |
| 49 | self.cause = cause |
| 50 | self.keys = keys |
| 51 | self.visited = visited |
| 52 | messages = list() |
| 53 | if keys is not None: |
| 54 | messages.append("Key not found: {}".format(keys)) |
| 55 | if visited is not None: |
| 56 | messages.append("Visited: {}".format(visited)) |
| 57 | messages.append("Cause:\n{}".format(cause)) |
| 58 | message = "\n".join(messages) |
| 59 | super().__init__(message) |
| 60 | |
| 61 | |
| 62 | def retrieve( |