code: public Object get(Object key) {
          if (key instanceof Number) {
              return get( ((Number)key).intValue() );
          }
          else {
              return null;
          }
      }
docs: Returns the value to which this map maps the specified key.  Returns
  <tt>null</tt> if the map contains no mapping for this key.  A return
  value of <tt>null</tt> does not <i>necessarily</i> indicate that the
  map contains no mapping for the key; it's also possible that the map
  explicitly maps the key to <tt>null</tt>.  The <tt>containsKey</tt>
  operation may be used to distinguish these two cases.
  
  @return the value to which this map maps the specified key.
  @param key key whose associated value is to be returned.