{{alias}}( obj, [options,] indicator )
    Group values according to an indicator function.

    When invoked, the indicator function is provided two arguments:

    - `value`: object value
    - `key`: object key

    The value returned by an indicator function should be a value which can be
    serialized as an object key.

    If provided an empty object, the function returns an empty object.

    The function iterates over an object's own properties.

    Key iteration order is *not* guaranteed, and, thus, result order is *not*
    guaranteed.

    Parameters
    ----------
    obj: Object|Array|TypedArray
        Input object to group.

    options: Object (optional)
        Options.

    options.thisArg: any (optional)
        Execution context.

    options.returns: string (optional)
        If `values`, values are returned; if `keys`, keys are returned; if `*`,
        both keys and values are returned. Default: 'values'.

    indicator: Function
        Indicator function indicating which group a value in the input object
        belongs to.

    Returns
    -------
    out: Object
        Group results.

    Examples
    --------
    > function indicator( v ) {
    ...     if ( v[ 0 ] === 'b' ) {
    ...         return 'b';
    ...     }
    ...     return 'other';
    ... };
    > var obj = { 'a': 'beep', 'b': 'boop', 'c': 'foo', 'd': 'bar' };
    > var out = {{alias}}( obj, indicator )
    { 'b': [ 'beep', 'boop', 'bar' ], 'other': [ 'foo' ] }

    // Output group results as keys:
    > var opts = { 'returns': 'keys' };
    > out = {{alias}}( obj, opts, indicator )
    { 'b': [ 'a', 'b', 'd' ], 'other': [ 'c' ] }

    // Output group results as key-value pairs:
    > opts = { 'returns': '*' };
    > out = {{alias}}( obj, opts, indicator )
    { 'b': [['a','beep'], ['b','boop'], ['d','bar']], 'other': [['c','foo' ]] }

    See Also
    --------