These helpers take two endpoints and return the sequence of all
integers within that interval. For `seq2_along()`

, the upper
endpoint is taken from the length of a vector. Unlike
`base::seq()`

, they return an empty vector if the starting point is
a larger integer than the end point.

## Arguments

- from
The starting point of the sequence.

- to
The end point.

- x
A vector whose length is the end point.

## Examples

```
seq2(2, 10)
#> [1] 2 3 4 5 6 7 8 9 10
seq2(10, 2)
#> integer(0)
seq(10, 2)
#> [1] 10 9 8 7 6 5 4 3 2
seq2_along(10, letters)
#> [1] 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
```