original_string: private function setCreatedAt(Carbon $createdAt = null)
      {
          if (is_null($createdAt)) {
              $createdAt = Carbon::now();
          }
  
          $this->createdAt = $createdAt;
      }
code: private function setCreatedAt(Carbon $createdAt = null)
      {
          if (is_null($createdAt)) {
              $createdAt = Carbon::now();
          }
  
          $this->createdAt = $createdAt;
      }
code_tokens: private function setCreatedAt ( Carbon $ createdAt = null ) { if ( is_null ( $ createdAt ) ) { $ createdAt = Carbon :: now ( ) ; } $ this -> createdAt = $ createdAt ; }
docstring: Set the creation date of the invoice, if null, set the current date.
  
  @param Carbon $createdAt | null
  
  @return void
docstring_tokens: Set the creation date of the invoice if null set the current date .