Simpy not showing other process name

I am trying to work my self into simpy. Which uses python generators to create sim steps.

From the documentation for simpy state access.

import simpy

def subfunc(env):
    print(env.active_process.name)   # will print "my_proc"

def my_proc(env):
    while True:
        print(env.active_process.name)   # will print "my_proc"
        yield env.process(subfunc(env))
        yield env.timeout(1)

env = simpy.Environment()
p1_result = env.process(my_proc(env))
print(type(env.active_process))  # None
env.step()
print(type(env.active_process))  # None

Is there an explenation why subfunc is printed out as my_proc ?

@AKX has been absolutly right

here a working code. With little boiler

    import simpy

    class NamedProcess:
        def __init__(self, name):
            self.process_name = name
        
        def __call__(self, env):
            return self.run(env)

    class SubFunc(NamedProcess):
        def run(self, env):
            print(f"Subfunc process name: {self.process_name}")
            yield env.timeout(1)

    class MyProc(NamedProcess):
        def run(self, env):
            while True:
                sub_proc = SubFunc("subfunc_process")
                print(f"Main process name: {self.process_name}")
                yield env.process(sub_proc(env))
                print(f"Main process name: {self.process_name}")
                yield env.timeout(1)

    env = simpy.Environment()
    my_proc = MyProc("my_proc")
    p1_result = env.process(my_proc(env))
    print(f"Process p1 created: {p1_result}")
    print(type(env.active_process))  # None
    env.step()
    print(type(env.active_process))  # None
    env.run(until=5)