{ "order":
  { "expression":
    { "type": "++"
    , "$1":
      { "type": "foreach"
      , "var": "dep"
      , "range": {"type": "FIELD", "name": "srcs"}
      , "body":
        { "type": "if"
        , "cond":
          { "type": "DEP_PROVIDES"
          , "dep": {"type": "var", "name": "dep"}
          , "provider": "keys"
          }
        , "then":
          { "type": "DEP_PROVIDES"
          , "dep": {"type": "var", "name": "dep"}
          , "provider": "keys"
          }
        , "else":
          { "type": "keys"
          , "$1":
            { "type": "map_union"
            , "$1":
              [ {"type": "DEP_RUNFILES", "dep": {"type": "var", "name": "dep"}}
              , { "type": "DEP_ARTIFACTS"
                , "dep": {"type": "var", "name": "dep"}
                }
              ]
            }
          }
        }
      }
    }
  }
}