/**
  * This method tests the "impl" method.
  */
 public function test_impl()
 {
     $x = IBool\Type::true();
     $y = IBool\Type::false();
     $z = IBool\Module::impl($x, $y);
     $this->assertInstanceOf('\\Saber\\Data\\IBool\\Type', $z);
     $this->assertSame(false, $z->unbox());
     $z = IBool\Module::impl($x, $x);
     $this->assertInstanceOf('\\Saber\\Data\\IBool\\Type', $z);
     $this->assertSame(true, $z->unbox());
     $z = IBool\Module::impl($y, $x);
     $this->assertInstanceOf('\\Saber\\Data\\IBool\\Type', $z);
     $this->assertSame(true, $z->unbox());
     $z = IBool\Module::impl($y, $y);
     $this->assertInstanceOf('\\Saber\\Data\\IBool\\Type', $z);
     $this->assertSame(true, $z->unbox());
 }