What is the purpose of the 'yield from' operator in Python and how is it used when working with generators?

The yield from operator in Python is used inside generators to delegate part of the generation to another generator or iterable object. This simplifies the code when you need to sequentially yield values from a nested generator.

Without yield from, you would have to write a loop that manually iterates over the nested generator and yields its values:

def generator1():
    yield 1
    yield 2

def generator2():
    for value in generator1():
        yield value
    yield 3

With yield from, this is shortened to:

def generator2():
    yield from generator1()
    yield 3

Thus, yield from <iterable> automatically iterates over all elements in <iterable> and passes them to the calling code. This improves readability and makes it easy to build complex generators from simple ones.