Generators in Python

example.py

def example():
    print('step 1')
    yield 1
    print('step 2')
    yield 2
    print('step 3')
    yield 3
    
g = example()

next(g)
# step 1
# 1
next(g)
# step 2
# 2
next(g)
# step 3
# 3
next(g)
# Traceback (most recent call last):
#   File "/usr/lib/python3.6/code.py", line 91, in runcode
#     exec(code, self.locals)
#   File "<input>", line 1, in <module>
# StopIteration