def METHOD_NAME(self, policy_string):
    """
     Convert a Boolean formula represented as a string into a policy represented like a tree.
    """
    assert type(policy_string) in [bytes, str], "invalid type for policy_string"
    if type(policy_string) == bytes:
        policy_string = policy_string.decode('utf-8')
    parser = PolicyParser()
    policy_obj = parser.parse(policy_string)
    _dictCount, _dictLabel = {}, {}
    parser.findDuplicates(policy_obj, _dictCount)
    for i in _dictCount.keys():
        if _dictCount[i] > 1: _dictLabel[i] = 0
    parser.labelDuplicates(policy_obj, _dictLabel)
    return policy_obj