If you define the predicate start() without parameters in your semantic model, it will be called automatically when you run the model through the context menu in the MPS project.
For example, the following start() predicate in the example about the Autodrome first sets up obstacles and road signs on the autodrome field, and then starts the graphical user interface by calling the another start domain function.
def start() means
check all
# set walls
AutodromeDSL.add wall(5, 1)
AutodromeDSL.add wall(5, 14)
AutodromeDSL.add wall(10, 8)
# set road signs
AutodromeDSL.add road sign(4, 5, "south")
AutodromeDSL.add road sign(6, 9, "north")
AutodromeDSL.add road sign(7, 7, "east")
AutodromeDSL.start(10, 500)
end
end def