* non-reified type or has bounds, {@code forDependants} is used to do further resolution, which
     * doesn't try to resolve any type variable on generic declarations that are already being
     * resolved.
     *
     * <p>Should only be called and overridden by {@link #resolve(TypeVariable)}.
     */
    Type resolveInternal(TypeVariable<?> var, TypeTable forDependants) {

    }
  }

  /**
   * Returns a new {@link TypeVariable} that belongs to {@code declaration} with {@code name} and
   * {@code bounds}.
   */
  static <D extends GenericDeclaration> TypeVariable<D> newArtificialTypeVariable(
      D declaration, String name, Type... bounds) {
    return newTypeVariableImpl(
        declaration, name, (bounds.length == 0) ? new Type[] {Object.class} : bounds);
  }

    }
  }

  /**
   * Returns a new {@link TypeVariable} that belongs to {@code declaration} with {@code name} and
   * {@code bounds}.
   */
  static <D extends GenericDeclaration> TypeVariable<D> newArtificialTypeVariable(
      D declaration, String name, Type... bounds) {
    return newTypeVariableImpl(
        declaration, name, (bounds.length == 0) ? new Type[] {Object.class} : bounds);
  }

     * non-reified type or has bounds, {@code forDependants} is used to do further resolution, which
     * doesn't try to resolve any type variable on generic declarations that are already being
     * resolved.
     *
     * <p>Should only be called and overridden by {@link #resolve(TypeVariable)}.
     */
    Type resolveInternal(TypeVariable<?> var, TypeTable forDependants) {

    * Add support for type annotations using `Optional` as in `param: Optional[str] = None`. New documentation: [Optional type declarations](https://fastapi.tiangolo.com/tutorial/query-params/#optional-type-declarations).
    * PR [#278](https://github.com/tiangolo/fastapi/pull/278).

## 0.26.0

* Separate error handling for validation errors.