def annotate(open_file, contents):
    """
    Add annotation to a single file
    """
    from corpkit.constants import PYTHON_VERSION
    contents = ''.join(contents)
    if PYTHON_VERSION == 2:
        contents = contents.encode('utf-8', errors='ignore')
    open_file.seek(0)
    open_file.write(contents)
    open_file.truncate()
