code: function union(array) {
        if (!isArray(array)) {
          arguments[0] = array ? nativeSlice.call(array) : arrayRef;
        }
        return uniq(concat.apply(arrayRef, arguments));
      }
docs: Computes the union of the passed-in arrays using strict equality for
  comparisons, i.e. `===`.
  
  @static
  @memberOf _
  @category Arrays
  @param {Array} [array1, array2, ...] Arrays to process.
  @returns {Array} Returns a new array of unique values, in order, that are
  present in one or more of the arrays.
  @example
  
  _.union([1, 2, 3], [101, 2, 1, 10], [2, 1]);
  // => [1, 2, 3, 101, 10]