what [T] means in nim?

[hany33]

type GraphMap[T] = ref object

> keyToNode: Table[T, Node]
> 
> nodeToKey: Table[Node, T]

proc newGraphMap[T](): GraphMap[T] =
    

result.new()

result.keyToNode = initTable[T, Node]()

result.nodeToKey = initTable[Node, T]()