Returns a dictionaries with the values stored in val2 of a diff dict.

def _get_val2_dict_from_diff_dict(diff_dict):
    '''
    Returns a dictionaries with the values stored in val2 of a diff dict.
    '''
    ret_dict = {}
    for p in diff_dict.keys():
        if not isinstance(diff_dict[p], dict):
            raise ValueError('Unexpected diff difct \'{0}\''.format(diff_dict))
        if 'val2' in diff_dict[p].keys():
            ret_dict.update({p: diff_dict[p]['val2']})
        else:
            ret_dict.update(
                {p: _get_val2_dict_from_diff_dict(diff_dict[p])})
    return ret_dict