### 6.3.1 Sizes of lists within a list

Recall that one thing that distinguishes lists from sequences is that a list can be an element of another list. The sizes command finds the length of elements of a list, as long as each element is a list.

- sizes takes L, a list each of whose elements is a list.
- sizes(L) returns the list of the lengths of the elements of L.

#### Example

sizes([[3,4],[2]])

| ⎡ ⎣ | 2,1 | ⎤ ⎦