I don't get why it would be inefficient. What is the alternative to just using `add`?
- Concatenation of seq and array? haoliang
- Concatenation of seq and array? Hlaaftana
- Concatenation of seq and array? sls1005
- Concatenation of seq and array? Hlaaftana
- Concatenation of seq and array? sls1005
- Concatenation of seq and array? Hlaaftana
- Concatenation of seq and array? sls1005
