Vectorized sum, similiar to `pmin`

and `pmax`

## Arguments

- ...
numeric vectors to sum

- na.rm
a logical indicating whether missing values should be removed

## Value

a vector with sum of `...`

arguments

## Examples

```
psum(c(1, 2, 3), c(4, 5, 6))
#> [1] 5 7 9
psum(c(1, 2, 3), pi)
#> [1] 4.141593 5.141593 6.141593
psum(c(1, NA, 3), c(4, 5, 6), na.rm = TRUE)
#> [1] 5 5 9
```