code: public XExpression getSyntacticReceiver(XExpression expression) {
  		if (expression instanceof XAbstractFeatureCall) {
  			if (expression instanceof XFeatureCall) {
  				return null;
  			}
  			if (expression instanceof XMemberFeatureCall) {
  				return ((XMemberFeatureCall) expression).getMemberCallTarget();
  			}
  			if (expression instanceof XAssignment) {
  				return ((XAssignment) expression).getAssignable();
  			}
  			if (expression instanceof XBinaryOperation) {
  				return ((XBinaryOperation) expression).getLeftOperand();
  			}
  			if (expression instanceof XUnaryOperation) {
  				return ((XUnaryOperation) expression).getOperand();
  			}
  			if (expression instanceof XPostfixOperation) {
  				return ((XPostfixOperation) expression).getOperand();
  			}
  		}
  		return null;
  	}
docs: /* @Nullable