How to use the nassl.SSL_FILETYPE_PEM function in nassl

# Sanity checks on the client cert options
        if bool(args_command_list.cert) ^ bool(args_command_list.key):
            raise CommandLineParsingError('No private key or certificate file were given. See --cert and --key.')

        # Private key and cert formats
        if args_command_list.certform == 'DER':
            args_command_list.certform = SSL_FILETYPE_ASN1
        elif args_command_list.certform == 'PEM':
            args_command_list.certform = SSL_FILETYPE_PEM
        else:
            raise CommandLineParsingError('--certform should be DER or PEM.')

        if args_command_list.keyform == 'DER':
            args_command_list.keyform = SSL_FILETYPE_ASN1
        elif args_command_list.keyform == 'PEM':
            args_command_list.keyform = SSL_FILETYPE_PEM
        else:
            raise CommandLineParsingError('--keyform should be DER or PEM.')

        # Let's try to open the cert and key files
        if args_command_list.cert:
            try:
                open(args_command_list.cert,"r")
            except:
                raise CommandLineParsingError('Could not open the client certificate file "' + str(args_command_list.cert) + '".')

        if args_command_list.key:
            try:
                open(args_command_list.key,"r")
            except:
                raise CommandLineParsingError('Could not open the client private key file "' + str(args_command_list.key) + '"')

"""
        Performs various sanity checks on the command line that was used to
        launch SSLyze.
        Returns the shared_settings object to be fed to plugins.
        """

        shared_settings = {}
        # Sanity checks on the client cert options
        if bool(args_command_list.cert) ^ bool(args_command_list.key):
            raise CommandLineParsingError('No private key or certificate file were given. See --cert and --key.')

        # Private key and cert formats
        if args_command_list.certform == 'DER':
            args_command_list.certform = SSL_FILETYPE_ASN1
        elif args_command_list.certform == 'PEM':
            args_command_list.certform = SSL_FILETYPE_PEM
        else:
            raise CommandLineParsingError('--certform should be DER or PEM.')

        if args_command_list.keyform == 'DER':
            args_command_list.keyform = SSL_FILETYPE_ASN1
        elif args_command_list.keyform == 'PEM':
            args_command_list.keyform = SSL_FILETYPE_PEM
        else:
            raise CommandLineParsingError('--keyform should be DER or PEM.')

        # Let's try to open the cert and key files
        if args_command_list.cert:
            try:
                open(args_command_list.cert,"r")
            except:
                raise CommandLineParsingError('Could not open the client certificate file "' + str(args_command_list.cert) + '".')