Fibonacci generator in Python

Generators produce values lazily - infinite sequences without infinite memory.

def fibonacci():
    a, b = 0, 1
    while True:
        yield a
        a, b = b, a + b

def take(gen, n):
    return [next(gen) for _ in range(n)]

How it works

1. Defines a generator that runs forever.
2. Each yield hands out the next Fibonacci number on demand.
3. take() pulls the first n values with next().

Keywords and builtins used here

• def
• fibonacci
• for
• next
• range
• return
• take
• while
• yield

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Step 2 of 7 in Iterators, errors & files, step 45 of 72 in Language basics.

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