Truncate the file and return the filename.

def prepare_file(filename):
    """Truncate the file and return the filename."""
    directory = os.path.join(utils.get_project_root(), "analyzation/")
    if not os.path.exists(directory):
        os.makedirs(directory)
    workfilename = os.path.join(directory, filename)
    open(workfilename, 'w').close()  # Truncate the file
    return workfilename