code: public function addApp(string $name, string $fqcn) : AviatorFile
      {
          $appName = strtolower($name);
  
          if (isset($this->apps[$appName])) {
              throw new \InvalidArgumentException("An app with the name '$appName' is already registered");
          }
  
          $this->apps[$appName] = $fqcn;
  
          return $this;
      }
docs: @param string $name
  @param string $fqcn
  
  @return AviatorFile