WPF customize DelegateCommand

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;

namespace WpfApp55.ViewModel
{
    public class VM : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        public void OnPropertyChanged(string propName)
        {
            var handler = PropertyChanged;
            if (handler != null)
            {
                handler(this, new PropertyChangedEventArgs(propName));
            }
        }

        private DelegateCommand UCCmdValue;
        public DelegateCommand UCCmd
        {
            get
            {
                if(UCCmdValue==null)
                {
                    UCCmdValue = new DelegateCommand(UCCmdExecuted, UCCmdCanExecute);
                }
                return UCCmdValue;
            }
        }

        private bool UCCmdCanExecute(object obj)
        {
            return true;
        }

        private void UCCmdExecuted(object obj)
        {
            MessageBox.Show("You had clicked the customized button!");
        }
    }
}

  public class DelegateCommand : ICommand
     {
         private readonly Predicate<object> _canExecute;
         private readonly Action<object> _execute;

         public event EventHandler CanExecuteChanged;

         public DelegateCommand(Action<object> execute)
                        : this(execute, null)
         {
         }

         public DelegateCommand(Action<object> execute,
                        Predicate<object> canExecute)
         {
             _execute = execute;
             _canExecute = canExecute;
         }

         public  bool CanExecute(object parameter)
         {
             if (_canExecute == null)
             {
                 return true;
             }

             return _canExecute(parameter);
         }

         public  void Execute(object parameter)
         {
             _execute(parameter);
         }

         public void RaiseCanExecuteChanged()
         {
             if (CanExecuteChanged != null)
             {
                 CanExecuteChanged(this, EventArgs.Empty);
             }
         }
     }