Call hierarchy for Python

I am using com.jetbrains.python.hierarchy.call.PyStaticCallHierarchyUtil#getCallees method to get the callees of a function.

However, I'm getting some weird results.

For this code snippet:

class A:
    def __init__(self):
        ...

    def foo(self, x):
        return x


class B(A):
    def foo(self, x):
        return D()


class D(A):
    def foo(self, x):
        b = B()
        b.foo(x)
        return A()


class C(A):
    def foo(self, x):
        y = D()
        y.foo(x)
        return self


def driver():
    x = A()
    i = 10
    while i > 0:
        x = x.foo(B())

I want to know the callees of D.foo. According to my observation, there should be only two callees of D.foo:

1. B.foo and
2. A.__init__

But PyStaticCallHierarchyUtil#getCallees returns 5 callees for D.foo. I also checked in the PyCharm IDE, same results there as well.

Clearly, the type of b in b = B() is class B.

def foo(self, x):
    b = B()
    b.foo(x)
    return A()

So, how come A.foo, C.foo, and D.foo are on the callee list of D.foo?

I would really appreciate any insight on this topic.