code: @Override
      public void _proximity(int proximity) {
          List<QueryToken> tokens = getCurrentWhereTokens();
          if (tokens.isEmpty()) {
              throw new IllegalStateException("Proximity can only be used right after search clause");
          }
  
          QueryToken whereToken = tokens.get(tokens.size() - 1);
          if (!(whereToken instanceof WhereToken)) {
              throw new IllegalStateException("Proximity can only be used right after search clause");
          }
  
          if (((WhereToken) whereToken).getWhereOperator() != WhereOperator.SEARCH) {
              throw new IllegalStateException("Proximity can only be used right after search clause");
          }
  
          if (proximity < 1) {
              throw new IllegalArgumentException("Proximity distance must be a positive number");
          }
  
          ((WhereToken) whereToken).getOptions().setProximity(proximity);
      }
docs: Specifies a proximity distance for the phrase in the last search clause
  <p>
  http://lucene.apache.org/java/2_4_0/queryparsersyntax.html#Proximity%20Searches
  @param proximity Proximity value