code: function centericMap(array, callback) {
    var retArray = [],
        length,
        left, right;
  
    if(array) {
      length = array.length - 1;
      left = length >> 1;
  
      while(left >= 0) {
        retArray[left] = callback(array[left]);
        right = length - left;
        if(right !== left) {
          retArray[right] = callback(array[right]);
        }
        left--;
      }
    }
    return retArray;
  }
docs: Iterates the array in a symmetric order, from middle to outwards
  @param array {Array} Array to be iterated
  @param callback {Function} Function to be called for each item
  @return A new array created with value returned by callback