public String findKey(String key){
  HeaderCard card=findCard(key);
  if (card == null) {
    return null;
  }
 else {
    return card.toString();
  }
}

public String findKey ( String key ) { HeaderCard card = findCard ( key ) ; if ( card == null ) { return null ; } else { return card . toString ( ) ; } }
find the card associated with a given key .
