You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: instructions.go
    path of file: ./repos/sliver/implant/vendor/golang.org/x/net/bpf
    
    the code of the file until where you have to start completion: // Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bpf

import "fmt"

// An Instruction is one instruction executed by the BPF virtual
// machine.
type Instruction interface {
	// Assemble assembles the Instruction into a Ra
    
func assembleLoad(dst Register, loadSize int, mode uint16, k uint32) (RawInstruction, error) {
	var (
		cls uint16
		sz  uint16
	)
	switch dst {
	case RegA:
		cls = opClsLoadA
	case RegX:
		cls = opClsLoadX
	default:
		return RawInstruction{}, fmt.Errorf("invalid target register %v", dst)
	}
	switch loadSize {
	case 1:
		sz = opLoadWidth1
	case 2:
		sz = opLoadWidth2
	case 4:
		sz = opLoadWidth4
	default:
		return RawInstruction{}, fmt.Errorf("invalid load byte length %d", sz)
	}
	return RawInstruction{
		Op: cls | sz | mode,
		K:  k,
	}, nil
}