docs: public final DRL5Expressions.expression_return expression() throws RecognitionException {
  		DRL5Expressions.expression_return retval = new DRL5Expressions.expression_return();
  		retval.start = input.LT(1);
  
  		BaseDescr left =null;
  		ParserRuleReturnScope right =null;
  
  		try {
  			// src/main/resources/org/drools/compiler/lang/DRL5Expressions.g:164:5: (left= conditionalExpression ( ( assignmentOperator )=>op= assignmentOperator right= expression )? )
  			// src/main/resources/org/drools/compiler/lang/DRL5Expressions.g:164:7: left= conditionalExpression ( ( assignmentOperator )=>op= assignmentOperator right= expression )?
  			{
  			pushFollow(FOLLOW_conditionalExpression_in_expression768);
  			left=conditionalExpression();
  			state._fsp--;
  			if (state.failed) return retval;
  			if ( state.backtracking==0 ) { if( buildDescr  ) { retval.result = left; } }
  			// src/main/resources/org/drools/compiler/lang/DRL5Expressions.g:165:9: ( ( assignmentOperator )=>op= assignmentOperator right= expression )?
  			int alt16=2;
  			switch ( input.LA(1) ) {
  				case EQUALS_ASSIGN:
  					{
  					int LA16_1 = input.LA(2);
  					if ( (synpred6_DRL5Expressions()) ) {
  						alt16=1;
  					}
  					}
  					break;
  				case PLUS_ASSIGN:
  					{
  					int LA16_2 = input.LA(2);
  					if ( (synpred6_DRL5Expressions()) ) {
  						alt16=1;
  					}
  					}
  					break;
  				case MINUS_ASSIGN:
  					{
  					int LA16_3 = input.LA(2);
  					if ( (synpred6_DRL5Expressions()) ) {
  						alt16=1;
  					}
  					}
  					break;
  				case MULT_ASSIGN:
  					{
  					int LA16_4 = input.LA(2);
  					if ( (synpred6_DRL5Expressions()) ) {
  						alt16=1;
  					}
  					}
  					break;
  				case DIV_ASSIGN:
  					{
  					int LA16_5 = input.LA(2);
  					if ( (synpred6_DRL5Expressions()) ) {
  						alt16=1;
  					}
  					}
  					break;
  				case AND_ASSIGN:
  					{
  					int LA16_6 = input.LA(2);
  					if ( (synpred6_DRL5Expressions()) ) {
  						alt16=1;
  					}
  					}
  					break;
  				case OR_ASSIGN:
  					{
  					int LA16_7 = input.LA(2);
  					if ( (synpred6_DRL5Expressions()) ) {
  						alt16=1;
  					}
  					}
  					break;
  				case XOR_ASSIGN:
  					{
  					int LA16_8 = input.LA(2);
  					if ( (synpred6_DRL5Expressions()) ) {
  						alt16=1;
  					}
  					}
  					break;
  				case MOD_ASSIGN:
  					{
  					int LA16_9 = input.LA(2);
  					if ( (synpred6_DRL5Expressions()) ) {
  						alt16=1;
  					}
  					}
  					break;
  				case LESS:
  					{
  					int LA16_10 = input.LA(2);
  					if ( (synpred6_DRL5Expressions()) ) {
  						alt16=1;
  					}
  					}
  					break;
  				case GREATER:
  					{
  					int LA16_11 = input.LA(2);
  					if ( (synpred6_DRL5Expressions()) ) {
  						alt16=1;
  					}
  					}
  					break;
  			}
  			switch (alt16) {
  				case 1 :
  					// src/main/resources/org/drools/compiler/lang/DRL5Expressions.g:165:10: ( assignmentOperator )=>op= assignmentOperator right= expression
  					{
  					pushFollow(FOLLOW_assignmentOperator_in_expression789);
  					assignmentOperator();
  					state._fsp--;
  					if (state.failed) return retval;
  					pushFollow(FOLLOW_expression_in_expression793);
  					right=expression();
  					state._fsp--;
  					if (state.failed) return retval;
  					}
  					break;
  
  			}
  
  			}
  
  			retval.stop = input.LT(-1);
  
  		}
  
  		catch (RecognitionException re) {
  		    throw re;
  		}
  
  		finally {
  			// do for sure before leaving
  		}
  		return retval;
  	}