code: public int add(T obj) {
          int ordinal = get(obj);
          if(ordinal != -1)
              return ordinal;
          
          if(size == objectsByOrdinal.length)
              growCapacity();
          
          objectsByOrdinal[size] = obj;
          hashOrdinalIntoArray(size, hashedOrdinalArray);
          
          return size++;
      }
docs: Add an object into this <code>OrdinalMap</code>.  If the same object (or an {@link Object#equals(Object)} object) is
  already in the map, then no changes will be made.
  
  @return the ordinal of <code>obj</code>