...
late_commands:
    maas: [wget, '--no-proxy', {{node_disable_pxe_url|escape.json}}, '--post-data', {{node_disable_pxe_data|escape.json}}, '-O', '/dev/null']
    add_python: ["curtin", "in-target", "--", "apt-get", "install", "python", "--yes", "--quiet"]
...