def subscript(text: str) -> str:
    """
    Return the *text* surrounded by subscript HTML tags.

    Subscript text appears half a character below the normal line,
    and is sometimes rendered in a smaller font.
    Subscript text can be used for chemical formulas.

        >>> subscript("foo")
        '<sub>foo</sub>'
    """
    return f"<sub>{text}</sub>"