pkg io/fs, const ModeAppend FileMode
pkg io/fs, const ModeCharDevice = 2097152
pkg io/fs, const ModeCharDevice FileMode
pkg io/fs, const ModeDevice = 67108864
pkg io/fs, const ModeDevice FileMode
pkg io/fs, const ModeDir = 2147483648
pkg io/fs, const ModeDir FileMode
pkg io/fs, const ModeExclusive = 536870912
pkg io/fs, const ModeExclusive FileMode
pkg io/fs, const ModeIrregular = 524288
pkg io/fs, const ModeIrregular FileMode

type I interface { m() }

func f(y I) {
	s := y.(string)        // illegal: string does not implement I (missing method m)
	r := y.(io.Reader)     // r has type io.Reader and the dynamic type of y must implement both I and io.Reader
	…
}
</pre>

<p>
A type assertion used in an <a href="#Assignment_statements">assignment statement</a> or initialization of the special form
</p>