dfs.py

graph = {
  'a' : ['b','c'],
  'b' : ['d'],
  'c' : ['e'],
  'd' : ['f'],
  'e' : [],
  'f' : [],
  'e': []
}

visited = {}

def dfs(at):
  if at in visited: return

  visited[at] = True
  print(f'at: {at}')

  neighbors = graph[at]

  for next_node in neighbors:
    dfs(next_node)

def containsX(at, target):
  pass

print(containsX('a', 'e'));