def capitalize(string):
    """Capitalize a sentence.

    Parameters
    ----------
    string : `str`
        String to capitalize.

    Returns
    -------
    `str`
        Capitalized string.

    Examples
    --------
    >>> capitalize('worD WORD WoRd')
    'Word word word'
    """
    if not string:
        return string
    if len(string) == 1:
        return string.upper()
    return string[0].upper() + string[1:].lower()
Capitalize a sentence.

    Parameters
    ----------
    string : `str`
        String to capitalize.

    Returns
    -------
    `str`
        Capitalized string.

    Examples
    --------
    >>> capitalize('worD WORD WoRd')
    'Word word word'