code: public boolean contains(Object value) {
      if (value == null) {
        throw new NullPointerException();
      }
  
      FastHashtableEntry tab[] = table;
      for (int i = tab.length ; i-- > 0 ;) {
        for (FastHashtableEntry e = tab[i] ; e != null ; e = e.next) {
          if (e.value.equals(value)) {
            return true;
          }
        }
      }
      return false;
    }
docs: Tests if some key maps into the specified value in this hashtable.
  This operation is more expensive than the <code>containsKey</code>
  method.
  
  @param      value   a value to search for.
  @return     <code>true</code> if some key maps to the
  <code>value</code> argument in this hashtable;
  <code>false</code> otherwise.
  @exception  NullPointerException  if the value is <code>null</code>.
  @see        java.util.Hashtable#containsKey(java.lang.Object)
  @since      JDK1.0