Rectangling data by unnesting list columns

df_unnamed <- tribble(
  ~x, ~y,
  1, list(11, 12, 13),
  2, list(21),
  3, list(31, 32),
)
df_unnamed

## # A tibble: 3 × 2
##       x y         
##   <dbl> <list>    
## 1     1 <list [3]>
## 2     2 <list [1]>
## 3     3 <list [2]>

Unnesting an unnamed list column? Make it longer!