func Read(f *File, b []byte) (n int, err error)

type error interface {
	Error() string
}

panic(42)
panic("unreachable")
panic(Error("cannot parse"))

package runtime

type Error interface {
	error
	// and perhaps other methods
}

type Reader interface {
	Read(p []byte) (n int, err error)
	Close() error
}

type Writer interface {
	Write(p []byte) (n int, err error)
	Close() error
}

// ReadWriter's methods are Read, Write, and Close.
type ReadWriter interface {
	Reader  // includes methods of Reader in ReadWriter's method set
	Writer  // includes methods of Writer in ReadWriter's method set
}

// A simple File interface.
interface {
	Read([]byte) (int, error)
	Write([]byte) (int, error)
	Close() error
}

func (p T) Read(p []byte) (n int, err error)
func (p T) Write(p []byte) (n int, err error)
func (p T) Close() error

type MyInt int

interface {
	~[]byte  // the underlying type of []byte is itself
	~MyInt   // illegal: the underlying type of MyInt is not MyInt
	~error   // illegal: error is an interface
}

func f(n int) (res int, err error) {
	if _, err := f(n-1); err != nil {
		return  // invalid return statement: err is shadowed
	}
	return
}

Types:
	any bool byte comparable
	complex64 complex128 error float32 float64
	int int8 int16 int32 int64 rune string
	uint uint8 uint16 uint32 uint64 uintptr

Constants:
	true false iota

Zero value:
	nil

Functions:
	append cap close complex copy delete imag len
	make new panic print println real recover