code: def get_new_edges(self, level):
          
          if level == 0:
              edges0 = [(0, 1), (0, 2)]
          elif level >= (self.max_size-1)//2:
              edges0 = []
          else:
              l2 = level*2
              edges0 = [(l2-1, l2+1), (l2, l2+2)]
          return edges0, []
docs: Get new edges from the pattern graph for the graph search algorithm
  
             The level argument denotes the distance of the new edges from the
             starting vertex in the pattern graph.