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: auth.go
    path of file: ./repos/scan4all/vendor/github.com/icodeface/tls
    
    the code of the file until where you have to start completion: // Copyright 2017 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 tls

import (
	"crypto"
	"crypto/ecdsa"
	"crypto/elliptic"
	"crypto/rsa"
	"encoding/asn1"
	"errors"
	"fmt"
	"hash"
	"io"
)

// pickSignatureAlg
    
func signatureSchemesForCertificate(version uint16, cert *Certificate) []SignatureScheme {
	priv, ok := cert.PrivateKey.(crypto.Signer)
	if !ok {
		return nil
	}

	switch pub := priv.Public().(type) {
	case *ecdsa.PublicKey:
		if version != VersionTLS13 {
			// In TLS 1.2 and earlier, ECDSA algorithms are not
			// constrained to a single curve.
			return []SignatureScheme{
				ECDSAWithP256AndSHA256,
				ECDSAWithP384AndSHA384,
				ECDSAWithP521AndSHA512,
				ECDSAWithSHA1,
			}
		}
		switch pub.Curve {
		case elliptic.P256():
			return []SignatureScheme{ECDSAWithP256AndSHA256}
		case elliptic.P384():
			return []SignatureScheme{ECDSAWithP384AndSHA384}
		case elliptic.P521():
			return []SignatureScheme{ECDSAWithP521AndSHA512}
		default:
			return nil
		}
	case *rsa.PublicKey:
		if version != VersionTLS13 {
			return []SignatureScheme{
				PSSWithSHA256,
				PSSWithSHA384,
				PSSWithSHA512,
				PKCS1WithSHA256,
				PKCS1WithSHA384,
				PKCS1WithSHA512,
				PKCS1WithSHA1,
			}
		}
		// RSA keys with RSA-PSS OID are not supported by crypto/x509.
		return []SignatureScheme{
			PSSWithSHA256,
			PSSWithSHA384,
			PSSWithSHA512,
		}
	default:
		return nil
	}
}