code: private String getNextTag(String str) {
          String tag;
          int endIndex;
          int tagIndex = str.indexOf("(");
  
          if( tagIndex < 0 ) {
              return null;
          }
  
          // in case there's nothing in the sentence
          endIndex = str.indexOf(" ", tagIndex);
  
          if( endIndex < 0 ) {
              return null;
          }
  
          tag = str.substring( tagIndex+1, endIndex ); 
  
          if( tag.length() > 0 ) {
              return tag;
          } else {
              str = str.substring( tagIndex+1 );
              return getNextTag(str);
          }
      }
docs: Returns the next tag in the sentence or null if there are no more tags
  @param str The sentence that the tag is extracted from