code: public static Searcher get(String variant) {
          final Searcher searcher = instances.get(variant);
          if (searcher == null) {
              throw new IllegalStateException(Errors.SEARCHER_GET_BEFORE_CREATE);
          }
          return searcher;
      }
docs: Gets the Searcher for a given variant.
  
  @param variant an identifier to differentiate this Searcher from eventual others.
  @return the corresponding Searcher instance.
  @throws IllegalStateException if no searcher was {@link #create(Searchable) created} before for this {@code variant}.