function bifurcateIn( obj, opts, predicate ) {
	var thisArg;
	var bool;
	var out;
	var key;
	var flg;
	var v;

	thisArg = opts.thisArg;
	out = [ [], [] ];
	flg = true;
	for ( key in obj ) { // eslint-disable-line guard-for-in
		flg = false;
		v = obj[ key ];
		bool = predicate.call( thisArg, v, key );
		if ( bool ) {
			out[ 0 ].push( [ key, v ] );
		} else {
			out[ 1 ].push( [ key, v ] );
		}
	}
	if ( flg ) {
		out.length = 0;
	}
	return out;
}
Splits values into two groups according to a predicate function and outputs results as key-value values.

## Notes

-   We need to cache the object value to prevent the edge case where, during the invocation of the predicate function, the value at key `k` is swapped for some other value. For some, that might be a feature; here, we take the stance that one should be less clever.

@private
@param {(Object|Array|TypedArray)} obj - input object
@param {Options} opts - function options
@param {*} [opts.thisArg] - execution context
@param {Function} predicate - predicate function indicating which group an element in the input object belongs to
@returns {(Array<Array>|Array)} results

@example
function predicate( v ) {
    return v[ 0 ] === 'b';
}

function Foo() {
    this.a = 'beep';
    this.b = 'boop';
    return this;
}

Foo.prototype = Object.create( null );
Foo.prototype.c = 'foo';
Foo.prototype.d = 'bar';

var obj = new Foo();

var out = bifurcateIn( obj, {}, predicate );
// e.g., returns [ [ [ 'a', 'beep' ], [ 'b', 'boop' ], [ 'd', 'bar' ] ], [ [ 'c', 'foo' ] ] ]