{{alias}}( str[, fromIndex] )
    Returns the previous extended grapheme cluster break in a string before a
    specified position.

    Parameters
    ----------
    str: string
        Input string.

    fromIndex: integer (optional)
        Position. Default: str.length-1.

    Returns
    -------
    out: integer
        Previous extended grapheme cluster break position.

    Examples
    --------
    > var out = {{alias}}( 'last man standing', 4 )
    3
    > out = {{alias}}( 'presidential election', 8 )
    7
    > out = {{alias}}( 'अनुच्छेद', 2 )
    0
    > out = {{alias}}( '🌷', 1 )
    -1

    See Also
    --------