private TvShow searchTvShowById(String tvShowId) {
    TvShow result = null;
    for (TvShow tvShow : tvShows) {
      if (tvShow.getTitle().equals(tvShowId)) {
        result = tvShow;
        break;
      }
    }
    return result;
  }
Search a TvShow using a tv show identifier.

We should return a clone of TvShow objects inside catalog because all this data is in
memory and anyone can change it. But, this is just a sample!

@param tvShowId used to search inside the catalog.
@return a TvShow that matches with the parameter passed as identifier.
parameter.
app/src/main/java/com/github/pedrovgs/effectiveandroidui/domain/tvshow/Catalog.java