Ive gota hierarchy like this:

inside Blocks.gd init() function I'm trying to access VoxelTerrain like this:
var _terrain : VoxelTerrain = $"../VoxelTerrain"
_terrain.restart_stream()
but I'm getting that _terrain is null.
Ive also tried:
var _terrain : VoxelTerrain = $"VoxelTerrain"
and
var _terrain : VoxelTerrain = get_node("/root/Main/VoxelTerrain")
but its always null.
It it not initialized yet?