code: public function addColumn(string $name, $value)
      {
          $this->args[] = $value;
          if (mb_strlen($this->columns) > 0) {
              $this->columns .= ", ";
          }
          $this->columns .= $name;
          if (mb_strlen($this->values) > 0) {
              $this->values .= ", ";
          }
          $argNum = count($this->args);
          $this->values .= "$".$argNum;
      }
docs: adds column to insert query
  @param string $name
  @param $value