public NextStepPCommand(PGradientViewModel wvm) : base(wvm)
 {
 }
 public SavePCommand(PGradientViewModel wvm) : base(wvm)
 {
 }
 public PGradientViewCommand(PGradientViewModel gvm)
 {
     _gvm = gvm;
 }
 public PreviousStepPCommand(PGradientViewModel wvm) : base(wvm)
 {
 }