Methods for the generic function `knots`

from the stats package
to obtain internal or boundary knots from the objects produced by this
package.

## Usage

```
# S3 method for class 'splines2'
knots(Fn, type = c("internal", "boundary"), ...)
```

## Examples

```
library(splines2)
set.seed(123)
x <- rnorm(100)
## B-spline basis
bsMat <- bSpline(x, df = 8, degree = 3)
## extract internal knots placed based on the quantile of x
(internal_knots <- knots(bsMat))
#> [1] -0.69135780 -0.32593159 0.06175631 0.43518149 0.99962119
## extract boundary knots placed based on the range of x
boundary_knots <- knots(bsMat, type = "boundary")
all.equal(boundary_knots, range(x))
#> [1] TRUE
```