AttributeError: Can't pickle local object 'SubPolicy.__init__.<locals>.<lambda>'

This error message indicates that you are trying to pickle (serialize) a local object named `lambda` that is defined inside the `__init__` method of a class named `SubPolicy`. Pickling local functions is not supported in Python by default and can lead to errors like this one.

To resolve this issue, you can define the `lambda` function outside of the `__init__` method, or you can use a different serialization method that supports pickling local functions, such as `dill` or `cloudpickle`. Here is an example of using `cloudpickle`:

import cloudpickle

# define your SubPolicy class here

# create an instance of SubPolicy
sub_policy = SubPolicy()

# serialize the object using cloudpickle
pickled_sub_policy = cloudpickle.dumps(sub_policy)

# deserialize the object
unpickled_sub_policy = cloudpickle.loads(pickled_sub_policy)

Note that using third-party serialization methods like `dill` or `cloudpickle` may have security implications, so make sure to use them only with trusted code.