{ "": {"type": "export", "target": "deep", "flexible_config": ["DEPTH"]}
, "deep":
  { "type": "generic"
  , "arguments_config": ["DEPTH"]
  , "deps": ["deep-output.py"]
  , "out_dirs": ["out"]
  , "cmds":
    [ { "type": "join_cmd"
      , "$1":
        ["python3", "deep-output.py", "out", {"type": "var", "name": "DEPTH"}]
      }
    ]
  }
}