Hi, community!

I am using the UpsetR package for finding intersections among the sets with the size of the intersection. For that I am using this tutorial. It instructs to make a list of vectors (where each vector is a set) and then convert the list to a matrix. It uses the following code:

```
lt = list(set1 = c("a", "b", "c"),
set2 = c("b", "c", "d", "e"))
list_to_matrix(lt)
```

But, when I use the same in my console, I find the following error:

```
> list_to_matrix(lt)
Error in list_to_matrix(lt) :
'list_to_matrix()' requires a list of numeric vectors
```

Can anyone please tell me how can I get rid of the error and proceed smoothly?

Thanks and regards,

DC7