* characters).
   *
   * @param c the character to escape
   * @return the replacement characters, or {@code null} if no escaping was required
   */
  // TODO(dbeaumont,cpovirk): Rename this something better once refactoring done
  protected abstract char @Nullable [] escapeUnsafe(char c);

      }

      return mapGenerator.create(entries.toArray()).keySet();
    }

    @Override
    public K[] createArray(int length) {
      // TODO: with appropriate refactoring of OneSizeGenerator, we can perhaps
      // tidy this up and get rid of the casts here and in
      // MapValueCollectionGenerator.

modifier, use it as base\n        ...(Popper.Defaults.modifiers[name] || {}),\n        // If there are custom options, override and merge with default ones\n        ...(options.modifiers ? options.modifiers[name] : {}),\n      };\n    });\n\n    // Refactoring modifiers' list (Object => Array)\n    this.modifiers = Object.keys(this.options.modifiers)\n      .map(name => ({\n        name,\n        ...this.options.modifiers[name],\n      }))\n      // sort the modifiers by order\n      .sort((a, b) => a.order...

   *
   * if (guardExpression) {
   *    throw new BadException(badMsg(...));
   * }
   *
   * The alternative natural refactorings into void or Exception-returning methods are much slower.
   * This is a big deal - we're talking factors of 2-8 in microbenchmarks, not just 10-20%. (This is