def get_experiment_type(filename):
    """
    Get the experiment type from the filename.

    The filename is assumed to be in the form of:
    '<reliability>_<durability>_<history kind>_<topic>_<timestamp>'

    :param filename: The filename to get the type.
    :return: A string where the timesptamp is taken out from the filename.
    """
    file_type = ''
    filename = filename.split('/')[-1]
    elements = filename.split('_')
    for i in range(0, len(elements) - 3):
        file_type += '{}_'.format(elements[i])
    file_type = file_type[:-1]
    return file_type