code: public function offsetExists($offset){
      
      if (is_null($this->result)) {
        $this->fetchData();
      }
      
      if(array_key_exists($offset,$this->result)){
        return true;
      }
      else{
        return false;
      }
      
    }
docs: Check if the key exists in the array
  
  ArrayAccess implementation
  
  @param mixed $offset
  @return boolean