polar Point                   // polar and Point denote different types
)

type TreeNode struct {
	left, right *TreeNode
	value any
}

type Block interface {
	BlockSize() int
	Encrypt(src, dst []byte)
	Decrypt(src, dst []byte)
}
</pre>

<p>
A defined type may have <a href="#Method_declarations">methods</a> associated with it.