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: curve25519_go120.go
    path of file: ./repos/goHackTools/vendor/golang.org/x/crypto/curve25519
    
    the code of the file until where you have to start completion: // Copyright 2022 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.

//go:build go1.20

package curve25519

import "crypto/ecdh"

func x25519(dst *[32]
    
func scalarMult(dst, scalar, point *[32]byte) {
	if _, err := x25519(dst, scalar[:], point[:]); err != nil {
		// The only error condition for x25519 when the inputs are 32 bytes long
		// is if the output would have been the all-zero value.
		for i := range dst {
			dst[i] = 0
		}
	}
}