proc simpleTreeDiff*[T, L, V](
    source, target: T,
    getLabel: proc(t: T): L,
    getValue: proc(t: T): V,
    valueScore: ScoreCmpProc[V],
    similarityTreshold: int = 60,
    initialMapping: bool = true
  ): auto =

  # ^^^^ implementation noise, included for context


  # vvvv if I have this *order of statements* things work fine
  let
    sourceIndex: TreeIndex[L, V] = makeIndex[T, L, V](
      source, true, getValue, getLabel)

  var tmp: Table[NodeId[L, V], NodeId[L, V]]

  let
    targetIndex: TreeIndex[L, V] = makeIndex[T, L, V](
      target, false, getValue, getLabel)



  # vvvv but if I move it like this, I get erro belov
  var tmp: Table[NodeId[L, V], NodeId[L, V]]
  let
    sourceIndex: TreeIndex[L, V] = makeIndex[T, L, V](
      source, true, getValue, getLabel)


  let
    targetIndex: TreeIndex[L, V] = makeIndex[T, L, V](
      target, false, getValue, getLabel)



#[
/mnt/workspace/github/hmisc/tests/tHTreeDistance.nim(36, 24) template/generic instantiation of `simpleTreeDiff` from here
/mnt/workspace/github/hmisc/src/hmisc/algo/htree_distance.nim(958, 54) template/generic instantiation of `makeIndex` from here
/mnt/workspace/github/hmisc/src/hmisc/algo/htree_distance.nim(163, 31) template/generic instantiation of `[]=` from here
/home/test/.choosenim/toolchains/nim-1.4.0/lib/pure/collections/tableimpl.nim(58, 21) template/generic instantiation of `rawGet` from here
/home/test/.choosenim/toolchains/nim-1.4.0/lib/pure/collections/hashcommon.nim(60, 48) Error: type mismatch: got <string, NodeId[system.string, system.string]>
but expected one of:
proc `==`(x, y: bool): bool
  first type mismatch at position: 1
  required type for x: bool
  but expression 't.data[h].key' is of type: string
proc `==`(x, y: char): bool
  first type mismatch at position: 1
  required type for x: char
  but expression 't.data[h].key' is of type: string
proc `==`(x, y: cstring): bool
  first type mismatch at position: 2
  required type for y: cstring
  but expression 'key' is of type: NodeId[system.string, system.string]
proc `==`(x, y: float): bool
  first type mismatch at position: 1
  required type for x: float
  but expression 't.data[h].key' is of type: string
proc `==`(x, y: float32): bool
  first type mismatch at position: 1
  required type for x: float32
  but expression 't.data[h].key' is of type: string
proc `==`(x, y: int): bool
  first type mismatch at position: 1
  required type for x: int
  but expression 't.data[h].key' is of type: string
proc `==`(x, y: int16): bool
  first type mismatch at position: 1
  required type for x: int16
  but expression 't.data[h].key' is of type: string
proc `==`(x, y: int32): bool
  first type mismatch at position: 1
  required type for x: int32
  but expression 't.data[h].key' is of type: string
proc `==`(x, y: int64): bool
  first type mismatch at position: 1
  required type for x: int64
  but expression 't.data[h].key' is of type: string
proc `==`(x, y: int8): bool
  first type mismatch at position: 1
  required type for x: int8
  but expression 't.data[h].key' is of type: string
proc `==`(x, y: pointer): bool
  first type mismatch at position: 1
  required type for x: pointer
  but expression 't.data[h].key' is of type: string
proc `==`(x, y: string): bool
  first type mismatch at position: 2
  required type for y: string
  but expression 'key' is of type: NodeId[system.string, system.string]
proc `==`(x, y: uint): bool
  first type mismatch at position: 1
  required type for x: uint
  but expression 't.data[h].key' is of type: string
proc `==`(x, y: uint16): bool
  first type mismatch at position: 1
  required type for x: uint16
  but expression 't.data[h].key' is of type: string
proc `==`(x, y: uint32): bool
  first type mismatch at position: 1
  required type for x: uint32
  but expression 't.data[h].key' is of type: string
proc `==`(x, y: uint64): bool
  first type mismatch at position: 1
  required type for x: uint64
  but expression 't.data[h].key' is of type: string
proc `==`(x, y: uint8): bool
  first type mismatch at position: 1
  required type for x: uint8
  but expression 't.data[h].key' is of type: string
proc `==`(x1, x2: XmlNode): bool
  first type mismatch at position: 1
  required type for x1: XmlNode
  but expression 't.data[h].key' is of type: string
proc `==`(x: string; y: type(nil) | type(nil)): bool
  first type mismatch at position: 2
  required type for y: typeof(nil) or typeof(nil)
  but expression 'key' is of type: NodeId[system.string, system.string]
proc `==`(x: type(nil) | type(nil); y: string): bool
  first type mismatch at position: 1
  required type for x: typeof(nil) or typeof(nil)
  but expression 't.data[h].key' is of type: string
proc `==`[A, B](tpl: (Option[A], Option[B]); tpl1: (A, B)): bool
  first type mismatch at position: 1
  required type for tpl: (Option[==.A], Option[==.B])
  but expression 't.data[h].key' is of type: string
proc `==`[Enum: enum](x, y: Enum): bool
  first type mismatch at position: 1
  required type for x: Enum: enum
  but expression 't.data[h].key' is of type: string
proc `==`[I, T](x, y: array[I, T]): bool
  first type mismatch at position: 1
  required type for x: array[I, T]
  but expression 't.data[h].key' is of type: string
proc `==`[T: proc](x, y: T): bool
  first type mismatch at position: 1
  required type for x: T: proc
  but expression 't.data[h].key' is of type: string
proc `==`[T: tuple | object](x, y: T): bool
  first type mismatch at position: 2
  required type for y: T: tuple or object
  but expression 'key' is of type: NodeId[system.string, system.string]
proc `==`[T](opt: Option[T]; val: T): bool
  first type mismatch at position: 1
  required type for opt: Option[==.T]
  but expression 't.data[h].key' is of type: string
proc `==`[T](x, y: openArray[T]): bool
  first type mismatch at position: 2
  required type for y: openArray[T]
  but expression 'key' is of type: NodeId[system.string, system.string]
proc `==`[T](x, y: ptr T): bool
  first type mismatch at position: 1
  required type for x: ptr T
  but expression 't.data[h].key' is of type: string
proc `==`[T](x, y: ref T): bool
  first type mismatch at position: 1
  required type for x: ref T
  but expression 't.data[h].key' is of type: string
proc `==`[T](x, y: seq[T]): bool
  first type mismatch at position: 1
  required type for x: seq[T]
  but expression 't.data[h].key' is of type: string
proc `==`[T](x, y: set[T]): bool
  first type mismatch at position: 1
  required type for x: set[T]
  but expression 't.data[h].key' is of type: string

expression: t.data[h].key == key

real    0m1.295s
user    0m1.223s
sys 0m0.069s

]#