How to use the onelogin.saml2.compat.to_bytes function in onelogin

def deflate_and_base64_encode(value):
        """
        Deflates and the base64 encodes a string
        :param value: The string to deflate and encode
        :type value: string
        :returns: The deflated and encoded string
        :rtype: string
        """
        return OneLogin_Saml2_Utils.b64encode(zlib.compress(compat.to_bytes(value))[2:-4])

def extract_tag_text(xml, tagname):
        open_tag = compat.to_bytes("<%s" % tagname)
        close_tag = compat.to_bytes("" % tagname)

        xml = OneLogin_Saml2_XML.to_string(xml)
        start = xml.find(open_tag)
        assert start != -1

        end = xml.find(close_tag, start) + len(close_tag)
        assert end != -1
        return compat.to_string(xml[start:end])

for line in lines:
            # Remove '\r' from end of line if present.
            line = line.rstrip()
            if line == '-----BEGIN CERTIFICATE-----':
                # Delete junk from before the certificate.
                data = ''
            elif line == '-----END CERTIFICATE-----':
                # Ignore data after the certificate.
                break
            elif line == '-----BEGIN PUBLIC KEY-----' or line == '-----BEGIN RSA PRIVATE KEY-----':
                # This isn't an X509 certificate.
                return None
            else:
                # Append the current line to the certificate data.
                data += line
        decoded_data = base64.b64decode(compat.to_bytes(data))

        if alg == 'sha512':
            fingerprint = sha512(decoded_data)
        elif alg == 'sha384':
            fingerprint = sha384(decoded_data)
        elif alg == 'sha256':
            fingerprint = sha256(decoded_data)
        else:
            fingerprint = sha1(decoded_data)

        return fingerprint.hexdigest().lower()

def b64encode(data):
        """base64 encode"""
        return compat.to_string(base64.b64encode(compat.to_bytes(data)))

:type: string

        :param debug: Activate the xmlsec debug
        :type: bool

        :return signed message
        :rtype str
        """

        if isinstance(msg, str):
            msg = msg.encode('utf8')

        xmlsec.enable_debug_trace(debug)
        dsig_ctx = xmlsec.SignatureContext()
        dsig_ctx.key = xmlsec.Key.from_memory(key, xmlsec.KeyFormat.PEM, None)
        return dsig_ctx.sign_binary(compat.to_bytes(msg), algorithm)

def extract_tag_text(xml, tagname):
        open_tag = compat.to_bytes("<%s" % tagname)
        close_tag = compat.to_bytes("" % tagname)

        xml = OneLogin_Saml2_XML.to_string(xml)
        start = xml.find(open_tag)
        assert start != -1

        end = xml.find(close_tag, start) + len(close_tag)
        assert end != -1
        return compat.to_string(xml[start:end])