<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def default_bundle_config():
 """Return the default bundle config file as an AttrDict."""


    import os
    from ambry.util import AttrDict

    config = AttrDict()
    f = os.path.join(
        os.path.dirname(
            os.path.realpath(__file__)),
        'bundle.yaml')

    config.update_yaml(f)

    return config