code: def seq_list_nested(b, d, x=0, top_level=True):
      '''
      Create a nested list of iteratively increasing values.
  
      b: branching factor
      d: max depth
      x: starting value (default = 0)
      '''
      x += 1
  
      if d == 0:
          ret = [x]
      else:
          val = x
          ret = []
          for i in range(b):
              lst, x = seq_list_nested(b, d-1, x, False)
              ret.extend(lst)
          ret = [val, ret]
              
      if top_level:
          return ret
      else:
          return ret, f seq_list_nested(b, d, x=0, top_level=True):
      '''
      Create a nested list of iteratively increasing values.
  
      b: branching factor
      d: max depth
      x: starting value (default = 0)
      '''
      x += 1
  
      if d == 0:
          ret = [x]
      else:
          val = x
          ret = []
          for i in range(b):
              lst, x = seq_list_nested(b, d-1, x, False)
              ret.extend(lst)
          ret = [val, ret]
              
      if top_level:
          return ret
      else:
          return ret, x
docs: Create a nested list of iteratively increasing values.
  
      b: branching factor
      d: max depth
      x: starting value (default = 0)