def open_file(filename, extension):
    """Loads arbitrary file.

    Parameters
    ----------
    filename : str
        Name of the file, excluding extension.
    extension : str
        File extension.

    Returns
    -------
    any
        Contents of the file.
    """
    with open(filename + '.' + extension, 'r') as opened_file:
        contents = opened_file.read()
    return contents