class_docstr: A directed graph where edges are one-way (a two-way edge can be represented by using two edges).
docstr: Determine if all nodes are reachable from node 0
docstr_tok: ["Determine","if","all","nodes","are","reachable","from","node","0"]
code: def dfs(self):
      """
      Determine if all nodes are reachable from node 0
      """
      visited = [False] * self.vertex_count
      self.dfs_util(0, visited)
      if visited == [True] * self.vertex_count:
          return True
      return False
  
file_path: keon-algos/algorithms/graph/check_digraph_strongly_connected.py
imports: from collections import defaultdict
label_desc: Use image node_id 3 for calling the Graph obj's underlying member method code with example usage: obj.dfs() and returns: False, True