在结构体嵌入接口

type reverse struct {
   // This embedded Interface permits Reverse to use the methods of
   // another Interface implementation.
   Interface
}

// Package sort provides primitives for sorting slices and user-defined collections.
package sort

// An implementation of Interface can be sorted by the routines in this package.
// The methods refer to elements of the underlying collection by integer index.
type Interface interface {
   // Len is the number of elements in the collection.
   Len() int

   // Less reports whether the element with index i
   // must sort before the element with index j.
   //
   // If both Less(i, j) and Less(j, i) are false,
   // then the elements at index i and j are considered equal.
   // Sort may place equal elements in any order in the final result,
   // while Stable preserves the original input order of equal elements.
   //
   // Less must describe a transitive ordering:
   //  - if both Less(i, j) and Less(j, k) are true, then Less(i, k) must be true as well.
   //  - if both Less(i, j) and Less(j, k) are false, then Less(i, k) must be false as well.
   //
   // Note that floating-point comparison (the < operator on float32 or float64 values)
   // is not a transitive ordering when not-a-number (NaN) values are involved.
   // See Float64Slice.Less for a correct implementation for floating-point values.
   Less(i, j int) bool

   // Swap swaps the elements with indexes i and j.
   Swap(i, j int)
}