{{alias}}( str, clbk[, thisArg] )
    Invokes a function for each grapheme cluster (i.e., user-perceived
    character) in a string.

    When invoked, the provided function is provided three arguments:

    - value: grapheme cluster.
    - index: starting grapheme cluster index.
    - str: input string.

    Parameters
    ----------
    str: string
        Input string over which to iterate.

    clbk: Function
        The function to invoke for each grapheme cluster in the input string.

    thisArg: any (optional)
        Execution context.

    Returns
    -------
    out: string
        Input string.

    Examples
    --------
    > var n = 0;
    > function fcn() { n += 1; };
    > {{alias}}( 'hello world!', fcn );
    > n
    12

    See Also
    --------