what namespace and reference should i add for INotifyPropertyChanged

i getting error message

the type or namespace name 'inotifypropertychanged' not found (are missing using directive or assembly reference?)

what namespace , reference should add inotifypropertychanged

any great

system.componentmodel

check below example:

using system.componentmodel;

namespace myapplicationnamespace
{
   public class myclass : inotifypropertychanged
   {
    public event propertychangedeventhandler propertychanged;

        protected void onpropertychanged(string propertyname)
        {
            if (propertychanged != null)
            {
                propertychanged(this, new propertychangedeventargs(propertyname));
            }
        }
   }
} 

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