I'm trying to get common characters from two separate vectors.

Example:

```
x <- c("abcde")
y <- c("efghi")
df <- data.frame(x, y)

```

Desired output

```
    x       y     z 
abcde   efghi     e     
lmnop   uvmxw     m

```

I've tried something like this, but it is a bad result:

```
df |> mutate(m = unique(x, y))

```

If there are multiple matches, returning a list would work great.