import json


def extract_from_file(filename, key_list=[]):
    """
    Assume `filename` is the path to a json file.
    Extract the data located by `key_list`.
    """

    f = open(filename,"r")
    file_data = json.load(f)
    f.close()
    for k in key_list:
        file_data = file_data[k]
    return file_data