code: function insert(firstArrayOrArgs, secondArrayOrArgs, indexOrAppend) {
      var firstArray = arraySlice.call(firstArrayOrArgs),
          secondArray = arraySlice.call(secondArrayOrArgs),
          spliceArgs;
  
      if(indexOrAppend === true) {
          return firstArray.concat(secondArray);
      }
  
      spliceArgs = [indexOrAppend, 0].concat(secondArray);
      firstArray.splice.apply(firstArray, spliceArgs);
      return firstArray;
  }
docs: Insert or append the second array/arguments into the
  first array/arguments.  This method does not alter
  the passed in array/arguments.
  
  @param  {Array/arguments} firstArrayOrArgs
  @param  {Array/arguments} secondArrayOrArgs
  @param  {Number/true} indexOrAppend true to append
  the second array to the end of the first one.  If it is a number
  insert the secondArray into the first one at the passed in index.
  @return {Array} the newly created array.
  
  Luc.Array.insert([0,4], [1,2,3], 1);
  >[0, 1, 2, 3, 4]
  Luc.Array.insert([0,4], [1,2,3], true);
  >[0, 4, 1, 2, 3]
  Luc.Array.insert([0,4], [1,2,3], 0);
  >[1, 2, 3, 0, 4]