code: function unitSamplerGenerator( seed ) {
  
  	// 32-bit xorshift, requires only a nonzero seed
  	// http://excamera.com/sphinx/article-xorshift.html
  	let sample = parseInt( generateHash( seed ), 16 ) || -1;
  	return function() {
  		sample ^= sample << 13;
  		sample ^= sample >>> 17;
  		sample ^= sample << 5;
  
  		// ECMAScript has no unsigned number type
  		if ( sample < 0 ) {
  			sample += 0x100000000;
  		}
  
  		return sample / 0x100000000;
  	};
  }
docs: Creates a seeded "sample" generator which is used for randomizing tests.