CIRCLE WITH A DOT

@fasterthanlime I want coloured function, user coloured and compiler enforced.
For example would be nice to mark functions as "blocking" (for whatever definition of blocking) and avoid them to be used by async unless enforced.
In embedded, in an interrupt, no other code can run or only other interrupt with higher priority if reentrant interrupt are supported and enabled.
this allow to call some simplified locking functions, but also you cant call locking that may hang...