Function optional

packages/effect/src/Schema.ts:2542–2547

(self: S)

 * @since 3.10.0
 */
export const optional = <S extends Schema.All>(self: S): optional<S> => {
  const ast = self.ast === AST.undefinedKeyword || self.ast === AST.neverKeyword
    ? AST.undefinedKeyword
    : UndefinedOr(self).ast
  return new PropertySignatureWithFromImpl(new PropertySignatureDeclaration(ast, true, true, {}, undefined), self)
}

/**
 * @category PropertySignature