inspect.isgeneratorfunction() returns wrong results

Question

I've been using inspect.isgeneratorfunction on my code successfully. Here's a simple example:

def f():
    for _ in range(5):
        yield "Hello World!"

inspect.isgeneratorfunction(f), inspect.isgeneratorfunction(blah.f) (when I store f in blah.py), and inspect.isgeneratorfunction(foo.f) (when blah is imported as foo), among others, all correctly return True as expected.

However, when I apply this to the following function from networkx, which has a similar structure, results are wrong: inspect.isgeneratorfunction(networkx.biconnected_components) returns False.

@not_implemented_for("directed")
def biconnected_components(G):
    """(docstring trimmed)"""
    for comp in _biconnected_dfs(G, components=True):
        yield set(chain.from_iterable(comp))

What am I missing?

Possibly relevant:

• I'm using Python 3.11.2 and networkx 2.8.8
• networkx.biconnected_components actually points to networkx.algorithms.components.biconnected.biconnected_components