Starred expressions

In most cases, mypy can infer the type of starred expressions from theright-hand side of an assignment, but not always:

  1. a, *bs = 1, 2, 3   # OK
  2. p, q, *rs = 1, 2   # Error: Type of rs cannot be inferred

On first line, the type of bs is inferred to beList[int]. However, on the second line, mypy cannot infer the typeof rs, because there is no right-hand side value for rs toinfer the type from. In cases like these, the starred expression needsto be annotated with a starred type:

  1. p, q, *rs = 1, 2  # type: int, int, List[int]

Here, the type of rs is set to List[int].