### current bpython session - make changes and save to reevaluate session.
### lines beginning with ### will be ignored.
### To return to bpython without reevaluating make no changes to this file
### or save an empty file.
class Int(int):
    def __call__(self, val):
        return Int(self + val)


num = Int(1)
num(2)
### 3
num(3)(4)(5)(6), 1 + 3 + 4 + 5 + 6
### (19, 19)


class CachedFibonacci:
    def __init__(self):
        self._cache = {}

    def __call__(self, n):
        nth = None
        if n in self._cache:
            return self._cache[n]
        elif n in [1, 0]:
            nth = 1
        else:
            nth = self(n-1) + self(n-2)
        self._cache[n] = nth
        return nth

fib = CachedFibonacci()
fib(3)
### 3
fib._cache
### {0: 1, 1: 1, 2: 2, 3: 3}
fib(6)
### 13
fib._cache
### {0: 1, 1: 1, 2: 2, 3: 3, 4: 5, 5: 8, 6: 13}
###