class_docstr: Graph.
  
  Args:
      nodes(`Dict[str, NodeRepr]`): The pipeline nodes from DAGRepr.nodes.
      edges(`Dict[str, Any]`): The pipeline edges from DAGRepr.edges.
      operator_pool(`OperatorPool`): The operator pool.
      thread_pool(`OperatorPool`): The ThreadPoolExecutor.
class_docstr_tok: ["Graph",".","Args",":","nodes","(","`","Dict","[","str",",","NodeRepr","]","`",")",":","The","pipeline","nodes","from","DAGRepr.nodes",".","edges","(","`","Dict","[","str",",","Any","]","`",")",":","The","pipeline","edges","from","DAGRepr.edges",".","operator_pool","(","`","OperatorPool","`",")",":","The","operator","pool",".","thread_pool","(","`","OperatorPool","`",")",":","The","ThreadPoolExecutor","."]
code: def _initialize(self):
      self._node_runners = []
      self._data_queues = dict(
          (
              name,
              DataQueue(
                  edge["data"],
                  keep_data=(
                      self._trace_edges
                      and self._trace_edges.get(name, False)
                  ),
              ),
          )
          for name, edge in self._edges.items()
      )
      for name in self._nodes:
          in_queues = [
              self._data_queues[edge]
              for edge in self._nodes[name].in_edges
          ]
          out_queues = [
              self._data_queues[edge]
              for edge in self._nodes[name].out_edges
          ]
          node = create_node(
              self._nodes[name],
              self._operator_pool,
              in_queues,
              out_queues,
              self._time_profiler,
          )
          if not node.initialize():
              raise RuntimeError(node.err_msg)
          self._node_runners.append(node)
  
imports: import re
  from typing import Dict, Any, Union, Tuple, List
  from concurrent.futures import ThreadPoolExecutor
  from towhee.tools import visualizers
  from towhee.utils.log import engine_log
  from .operator_manager import OperatorPool
  from .data_queue import DataQueue
  from .dag_repr import DAGRepr
  from .nodes import create_node, NodeStatus
  from .node_repr import NodeRepr
  from .time_profiler import TimeProfiler, Event
label_desc: Use image node_id 2 for calling the _Graph obj's underlying member method code with example usage: obj._initialize() without return types