class_docstr: A tree implementation.
class_docstr_tok: ["A","tree","implementation","."]
docstr: Set up the tree.
docstr_tok: ["Set","up","the","tree","."]
code: def __init__(self):
      """Set up the tree."""
      self._root = Node(None)
  
      # keep a flat dictionary of nodes contained in the tree for better
      # __contains__
      self._all_nodes = _DataIDContainer()
  
imports: from __future__ import annotations
  from typing import Container, Iterable, Optional
  import numpy
  from satpy import DataID, DatasetDict
  from satpy.dataset import ModifierTuple, create_filtered_query
  from satpy.dataset.data_dict import TooManyResults, get_key
  from satpy.node import EMPTY_LEAF_NAME, LOG, CompositorNode, MissingDependencies, Node, ReaderNode
label_desc: Use image node_id 1 to create a new Tree object  with example: obj = Tree()