code: public boolean containsValue(Object value) {
          Entry tab[] = table;
          
          if (value==null) {
              for (int i = tab.length ; i-- > 0 ;) {
                  for (Entry e = tab[i] ; e != null ; e = e.next) {
                      if (e.value == null) {
                          return true;
                      }
                  }
              }
          } 
          else {
              for (int i = tab.length ; i-- > 0 ;) {
                  for (Entry e = tab[i] ; e != null ; e = e.next) {
                      if (value.equals(e.value)) {
                          return true;
                      }
                  }
              }
          }
          
          return false;
      }
docs: Returns <tt>true</tt> if this map maps one or more keys to the
  specified value.
  
  @param value value whose presence in this map is to be tested.
  @return <tt>true</tt> if this map maps one or more keys to the
  specified value.