public void replaceParameters(Map<Object, Object> params) {
    fromClause.replaceParameters(params);

    if (whereClause != null) {
      whereClause.replaceParameters(params);
    }

    if (limit != null) {
      limit.replaceParameters(params);
    }
    if (batch != null) {
      batch.replaceParameters(params);
    }
  }
 @Override
 public String toString() {
   StringBuilder result = new StringBuilder();
   result.append("DELETE VERTEX ");
   result.append(fromClause.toString());
   if (returnBefore) {
     result.append(" RETURN BEFORE");
   }
   if (whereClause != null) {
     result.append(" WHERE ");
     result.append(whereClause.toString());
   }
   if (limit != null) {
     result.append(limit);
   }
   if (batch != null) {
     result.append(batch);
   }
   return result.toString();
 }