message: Add option for STANC3 dev mode - set the STANC3 env variable to the path to your stanc3 code and it will attempt to build and use that binary.
diff: @@ -12,7 +12,13 @@ else
  endif
  +ifeq ($(STANC3),)
  bin/stanc$(EXE) :
  @mkdir -p $(dir $@)
  curl -L https://github.com/stan-dev/stanc3/releases/download/nightly/$(OS_TAG)-stanc -o bin/stanc
  chmod +x bin/stanc
  +else
  +bin/stanc$(EXE) : $(shell find $(STANC3)/src/ -type f -name '*.ml*') $(STANC#)
  + cd $(STANC3) && echo "--- Rebuilding stanc ---\n" && dune build @install
  + cp $(STANC3)/_build/default/src/stanc/stanc.exe $@
  +endif
  \ No newline at end of file
  