| 116 | |
| 117 | |
| 118 | class _Node(object): |
| 119 | def __init__(self, data): |
| 120 | self.prev = None |
| 121 | self.next = None |
| 122 | self.data = data |
| 123 | |
| 124 | def append(self, data): |
| 125 | node = _Node(data) |
| 126 | |
| 127 | curr_next = self.next |
| 128 | |
| 129 | node.next = self.next |
| 130 | node.prev = self |
| 131 | self.next = node |
| 132 | |
| 133 | if curr_next is not None: |
| 134 | curr_next.prev = node |
| 135 | |
| 136 | return node |
| 137 | |
| 138 | def prepend(self, data): |
| 139 | node = _Node(data) |
| 140 | |
| 141 | curr_prev = self.prev |
| 142 | |
| 143 | node.prev = self.prev |
| 144 | node.next = self |
| 145 | self.prev = node |
| 146 | |
| 147 | if curr_prev is not None: |
| 148 | curr_prev.next = node |
| 149 | |
| 150 | return node |
| 151 | |
| 152 | |
| 153 | class _HelperBytecodeList(object): |