parallax property
      
      Parallax?
      get
      parallax
      
    
    
    
Implementation
Parallax? get parallax => _parallax;
      
      set
      parallax
      (Parallax? p) 
      
    
    
    
Implementation
set parallax(Parallax? p) {
  _parallax = p;
  _parallax?.resize(size);
}