[cairo] Shouldn't Cairo use/offer degrees rather than radians?

[Lawrence D'Oliveiro]

I wrote:

>     (ctx
>         .arc(centre = (25, 25), radius = 20, angle1 = -180 * qah.deg, angle2 = 0, negative = False)
>         .stroke()
>         .arc(centre = (25, 25), radius = 20, angle1 = 0, angle2 = 180 * qah.deg, negative = False)
>         .stroke()
>     )

I tried changing the two arc calls to

    .arc(centre = (25, 25), radius = 20, angle1 = -90 * qah.deg, angle2 = 90 * qah.deg, negative = False)

and

    .arc(centre = (25, 25), radius = 20, angle1 = 90 * qah.deg, angle2 = 270 * qah.deg, negative = False)

and this made no difference that I could see. So starting and stopping
angles at arbitrary multiples of 90° work just fine.