6.40.1  Sizes of a list of lists: sizes

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 one argument:
  L, a list each of whose elements is a list.
• sizes(L) returns the list of the lengths of the elements of L.

Example.
Input:

Output: