import re


def label_func(filename):
    """
    Returns the corresponding label of a file given its filename.
    
    :param filename: (Path) path to file of interest
    :return: (str) label that corresponds to file/data of interest
    """
    if int(re.split('_|p', str(filename))[1]) == 0:
        return 'straight'
    elif '-' in str(filename):
        return 'right'
    else:
        return 'left'