A practical use case of a generator is to iterate through values of an infinite series. Here's an example of finding the first ten terms of the Fibonacci Sequence.
def fib(a=0, b=1):
"""Generator that yields Fibonacci numbers. `a` and `b` are the seed values"""
while True:
yield a
a, b = b, a + b
f = fib()
print(', '.join(str(next(f)) for _ in range(10)))
0, 1, 1, 2, 3, 5, 8, 13, 21, 34