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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def _list_items(action, key, profile=None, subdomain=None, api_key=None):
    '''
    List items belonging to an API call.

    This method should be in utils.pagerduty.
    '''
    items = _query(
        profile=profile,
        subdomain=subdomain,
        api_key=api_key,
        action=action
    )
    ret = {}
    for item in items[action]:
        ret[item[key]] = item
    return ret