drakon_gen.tcl is a command-line utility that generates code from a .drn file.
./drakon_gen.tcl -in examples/Python/python_demo.drn
This one will generate a file called python_demo.py in examples/Python.
./drakon_gen.tcl -in examples/Python/python_demo.drn -out .
This one will generate a file called python_demo.py and put it in the current folder.
In order for code generation to work, the .drn files must have a programming language selected in its properties.
To choose the language for the .drn file, open it in DRAKON Editor, go to File / File properties...