Add stop options

[leonbett]

These are useful for setting up Fandango experiments, as explained in the comments.

[github-actions]

Bencher Report

Branch	stop_options
Testbed	ubuntu-latest

🚨 2 Alerts

Benchmark	Measure Units	View	Benchmark Result (Result Δ%)	Upper Boundary (Limit %)
tests/test_benchmarks.py::test_init_fandango	Latency milliseconds (ms)	📈 plot 🚷 threshold 🚨 alert (🔔)	162.07 ms (+7.42%) Baseline: 150.88 ms	161.83 ms (100.15%)
tests/test_benchmarks.py::test_parse_spec	Latency milliseconds (ms)	📈 plot 🚷 threshold 🚨 alert (🔔)	162.13 ms (+6.14%) Baseline: 152.76 ms	160.95 ms (100.73%)

Click to view all benchmark results

Benchmark	Latency	Benchmark Result milliseconds (ms) (Result Δ%)	Upper Boundary milliseconds (ms) (Limit %)
tests/test_benchmarks.py::test_generate_with_single_hard_constraint	📈 view plot 🚷 view threshold	1,480.37 ms (-10.66%) Baseline: 1,656.99 ms	2,693.28 ms (54.97%)
tests/test_benchmarks.py::test_generate_with_single_soft_constraint	📈 view plot 🚷 view threshold	52,616.31 ms (+6.45%) Baseline: 49,425.94 ms	87,460.27 ms (60.16%)
tests/test_benchmarks.py::test_init_fandango	📈 view plot 🚷 view threshold 🚨 view alert (🔔)	162.07 ms (+7.42%) Baseline: 150.88 ms	161.83 ms (100.15%)
tests/test_benchmarks.py::test_parse_spec	📈 view plot 🚷 view threshold 🚨 view alert (🔔)	162.13 ms (+6.14%) Baseline: 152.76 ms	160.95 ms (100.73%)

🐰 View full continuous benchmarking report in Bencher

[riesentoaster]

We should probably also add this to the docs somewhere. @andreas-zeller what do you think? Suggestions?

[riesentoaster]

The arg here shouldn't be a string to be evaled, it should be the optional parsed function. And the same applies to the outside interface. And if the arg isn't passed in the command line, this should be an empty optional and not a constant function, just like in downstream calls.