docs: public final AntlrDatatypeRuleToken ruleFieldModifier() throws RecognitionException {
          AntlrDatatypeRuleToken current = new AntlrDatatypeRuleToken();
  
          Token kw=null;
  
  
          	enterRule();
  
          try {
              // InternalSARL.g:9770:2: ( (kw= 'val' | kw= 'var' ) )
              // InternalSARL.g:9771:2: (kw= 'val' | kw= 'var' )
              {
              // InternalSARL.g:9771:2: (kw= 'val' | kw= 'var' )
              int alt253=2;
              int LA253_0 = input.LA(1);
  
              if ( (LA253_0==66) ) {
                  alt253=1;
              }
              else if ( (LA253_0==65) ) {
                  alt253=2;
              }
              else {
                  if (state.backtracking>0) {state.failed=true; return current;}
                  NoViableAltException nvae =
                      new NoViableAltException("", 253, 0, input);
  
                  throw nvae;
              }
              switch (alt253) {
                  case 1 :
                      // InternalSARL.g:9772:3: kw= 'val'
                      {
                      kw=(Token)match(input,66,FOLLOW_2); if (state.failed) return current;
                      if ( state.backtracking==0 ) {
  
                        			current.merge(kw);
                        			newLeafNode(kw, grammarAccess.getFieldModifierAccess().getValKeyword_0());
                        		
                      }
  
                      }
                      break;
                  case 2 :
                      // InternalSARL.g:9778:3: kw= 'var'
                      {
                      kw=(Token)match(input,65,FOLLOW_2); if (state.failed) return current;
                      if ( state.backtracking==0 ) {
  
                        			current.merge(kw);
                        			newLeafNode(kw, grammarAccess.getFieldModifierAccess().getVarKeyword_1());
                        		
                      }
  
                      }
                      break;
  
              }
  
  
              }
  
              if ( state.backtracking==0 ) {
  
                	leaveRule();
  
              }
          }
  
              catch (RecognitionException re) {
                  recover(input,re);
                  appendSkippedTokens();
              }
          finally {
          }
          return current;
      }