cs61a

fib.py

class VirFib():
    """A Virahanka Fibonacci number.

    >>> start = VirFib()
    >>> start
    VirFib object, value 0
    >>> start.next()
    VirFib object, value 1
    >>> start.next().next()
    VirFib object, value 1
    >>> start.next().next().next()
    VirFib object, value 2
    >>> start.next().next().next().next()
    VirFib object, value 3
    >>> start.next().next().next().next().next()
    VirFib object, value 5
    >>> start.next().next().next().next().next().next()
    VirFib object, value 8
    >>> start.next().next().next().next().next().next() # Ensure start isn't changed
    VirFib object, value 8
    """

    def __init__(self, value=0):
        self.value = value

    def next(self):
        "*** YOUR CODE HERE ***"
        ans = VirFib(int(not self.value) or self.value + self.prev)
        ans.prev = self.value
        return ans

    def __repr__(self):
        return "VirFib object, value " + str(self.value)

import doctest; doctest.testmod()