Functions that use yield are known as "generators". Before Python 3.3, generators cannot return values. Similarly,
functions that use return cannot use yield. Doing so will cause a SyntaxError.
Either upgrade your version of Python to a version >= 3.3, or don’t use both return and yield in a function.
Noncompliant code example
def adder(n):
num = 0
while num < n:
yield num
num += 1
return num #Noncompliant
