Return string containing the contents of the file at *relpath* relative to
    this file.

def text_of(relpath):
    """
    Return string containing the contents of the file at *relpath* relative to
    this file.
    """
    thisdir = os.path.dirname(__file__)
    file_path = os.path.join(thisdir, os.path.normpath(relpath))
    with open(file_path) as f:
        text = f.read()
    return text