13 lines
368 B
Python
13 lines
368 B
Python
class Stack:
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def __init__(self):
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self._first = None
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def __nonzero__(self):
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return self._first is not None
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def append(self, value):
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self._first = (value, self._first)
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def pop(self):
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if self._first is None:
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raise IndexError, "pop from empty stack"
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value, self._first = self._first
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return value
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