code: function remove(arr1, arr2) {
    if (!Array.isArray(arr1) || !Array.isArray(arr2)) {
      throw new Error('expected both arguments to be arrays');
    }
    var result = [];
    var len = arr1.length;
    for (var i = 0; i < len; i++) {
      var elem = arr1[i];
      if (arr2.indexOf(elem) == -1) {
        result.push(elem);
      }
    }
    return result;
  }
docs: /*
  remove([1, 2, 3, 4, 5, 6], [1, 3, 6]); // [2, 4, 5]