def next_node(node_num):
  next_nodes = []
  for edge in tree:
    if edge[0] == node_num:
      next_nodes.append(edge[1])
  return next_nodes

def all_nodes(num):
  x = [] 
  add_nodes = next_node(num)
  while add_nodes != []:
    for i in add_nodes:
      add_nodes += next_node(i) 
      x += add_nodes
      add_nodes = []
  return x
