Interleave Python and R

[Chuck McCallum]

In this PR:

• #1262

tabbed Python and R examples are introduced. I looked for a bit, but couldn't find a way to have the runnable R examples inline. So instead the R examples are included (with literalinclude), and the Python doctests are still in the .rst.

This works well enough, but it is hard to confirm that the python and R examples are running in parallel: It would be easy to tweak one, and forget the other.

Proposal: Interleave the Python and R in one .R file: Protect the python doctests by putting them in multi-line R strings. We'll need to make sure the .R files are scanned for python doctests, but otherwise should work smoothly. Something like:

'
# p-1
>>> from opendp.mod import enable_features
>>> enable_features('contrib')

# p-1-end
'

# r-1
library(opendp)
enable_features("contrib")
# r-1-end

'
# p-2
>>> import opendp.prelude as dp
>>> base_laplace = dp.space_of(float) >> dp.m.then_base_laplace(scale=1.)
>>> dp_agg = base_laplace(23.4)

# p-2-end
'

# r-2
space <- c(atom_domain(.T = "f64"), absolute_distance(.T = "f64"))
base_laplace <- space |> then_base_laplace(1.)
dp_agg <- base_laplace(arg = 23.4)
# r-2-end

I'm not sure about this -- both approaches are somewhat awkward. Feedback welcome.

[Chuck McCallum]

Decided interleaving won't be sustainable with more languages... and even with examples of the the two python APIs in parallel: Instead, pull out python examples.