Easily switch off preCICE

Oftentimes, you want to run a coupled code in single-physics mode, so without preCICE. For codes like OpenFOAM or FEniCS, we would handle this in the adapter. As the Python bindings are also used in codes without adapters (e.g. Nutils) and the codes don't need compiling (Python), it would be really great if there was a simple "switch off" mechanism.

Say

import precice
precice.turn_off()
...
interface = precice.Interface("Solid", "../precice-config.xml", 0, 1)
...
vertex_ids = interface.set_mesh_vertices(mesh_id, vertices)

Then all preCICE calls should be NOPs.
This prevents us from polluting compact codes with a lot of

if(precice_used):
   interface = precice.Interface("Solid", "../precice-config.xml", 0, 1)

Is there a standard Python way how to do this? If not, could we handle it in the Python bindings?

I don't think we need this feature for other bindings as there we have longer codes and/or adapters and we compile. Do you agree?

Start by inspecting the public precice module and the Interface entry point shown in the example. Determine how a turn_off state would affect Interface construction and subsequent calls, then verify that all preCICE calls become no-ops while single-physics Python code continues normally.