code: public String optString(int index){
  		LazyNode token=getOptionalValueToken(index);
  		if(token==null)return null;
  		if(token.type==LazyNode.VALUE_NULL)return null;
  		return token.getStringValue();
  	}
docs: Returns the string value stored at the given index or null if there was no such value.
  
  @param index the location of the value in this array
  @return the value if it could be parsed as a boolean or null if there was no such value
  @throws LazyException if the index is out of bounds