Plot basis spline functions

## Arguments

- knots
A vector of values between 0 and 1, specifying cut-points for splines

- degree
Integer specifying degree of curvature.

## Value

A ggplot object that contains a plot of the basis functions. In total, there
will be length(knots) + degree + 1 functions plotted.

## Examples

```
knots <- c(0.25, 0.50, 0.75)
viewBasis(knots, degree = 1)
knots <- c(0.25, 0.50, 0.75)
viewBasis(knots, degree = 2)
knots <- c(0.25, 0.50, 0.75)
viewBasis(knots, degree = 3)
```