How to solve OpenAI gym's 'Module has no attribute error'

Question

I follow the exact same folder structure for OpenAI Gym but still get attribute not found error upon using gym.make(). My folder structure is as below.

my_gym
  -->examples
      ---MAIN_ENV 
  -->my_rl_gym
        --->envs
               ---__init__
               ---main_env    #contains a class called Myxyz as registered below
        ---__init__

  -->setup.ipynb

The below is how I register in the __init__ inside envs folder

from gym.envs.registration import register

register(
     id='XYZ-v0',
     entry_point='my_rl_gym.envs:Myxyz'
)

The below is in the __init__ inside my_rl_gym folder i.e. outside envs

# from my_rl_gym.envs.main_env import Myxyz

#### THIS above line is actually correct BUT gives error as No module named 
#####'my_rl_gym.envs.main_env ' . Hence, I changed this to below line.

import main_env 

The error comes upon calling the make command

env = gym.make('XYZ-v0', **env_args)

Traceback is:

----> 6 env = gym.make('XYZ-v0', **env_args)
      
~\anaconda3\lib\site-packages\gym\envs\registration.py in make(id, **kwargs)
    674 # fmt: on
    675 def make(id: str, **kwargs) -> "Env":
--> 676     return registry.make(id, **kwargs)
    677 
    678 

~\anaconda3\lib\site-packages\gym\envs\registration.py in make(self, path, **kwargs)
    518         spec = self.spec(path)
    519         # Construct the environment
--> 520         return spec.make(**kwargs)
    521 
    522     def all(self):

~\anaconda3\lib\site-packages\gym\envs\registration.py in make(self, **kwargs)
    137             env = self.entry_point(**_kwargs)
    138         else:
--> 139             cls = load(self.entry_point)
    140             env = cls(**_kwargs)
    141 

~\anaconda3\lib\site-packages\gym\envs\registration.py in load(name)
     54     mod_name, attr_name = name.split(":")
     55     mod = importlib.import_module(mod_name)
---> 56     fn = getattr(mod, attr_name)
     57     return fn
     58 

AttributeError: module 'my_rl_gym.envs' has no attribute 'Myxyz'

What is the problem here? The folder directories are correct and the way of defining is also correct. For e.g. see https://github.com/MartinThoma/banana-gym Is it because I need to have any setup file? because if so then I did and got the typeerror as in question Getting Type error with setup file in OpenAI gym