def prepend_license(license_text, src_text, file_extension):
    """Prepend a license notice to the file commented out based on the extension.

    Args:
        src_text (str): The text which will have the license prepended.
        file_extension (str): The relevant file extension.

    Returns:
        str: The full text of the prepended file.
    """
    # opening, new line prepend, closing
    comment_symbols = {
        ".css": ("/*", " * ", " */"),
        ".html": ("<!--", "  ", "-->"),
        ".js": ("/*", " * ", " */"),
    }

    ext = file_extension.lower()

    if ext not in comment_symbols:
        return src_text

    com = comment_symbols[ext]

    lic = "\n".join(("".join((com[1], line)) for line in license_text))
    lic = "\n".join((com[0], lic, com[2]))

    if ext == ".html":
        lic = "\n".join(("{#", lic, "#}"))

    src_text = "\n".join((lic, src_text))

    return src_text