After a while, he shows the example of a find function

  def find(seq, target):
    for i, value in enumerate(seq):
      if value == target
        break
    else:
      return -1
    return i

Can't you just remove the whole break and else thing and just do this?

  def find(seq, target):
    for i, value in enumerate(seq):
      if value == target:
        return i
    return -1