{ "out":
  { "type": ["@", "rules", "shell", "cmds"]
  , "outs": ["out.txt"]
  , "cmds": ["./hello > out.txt"]
  , "deps": [["hello", ""]]
  }
, "":
  { "type": ["@", "rules", "shell", "cmds"]
  , "outs": ["wc.txt", "tr.txt"]
  , "cmds": ["wc out.txt > wc.txt", "cat out.txt | tr a-z A-Z > tr.txt"]
  , "deps": ["out"]
  }
}