Okay, I can see that I have no business writing macros at my level of understanding since I can’t even follow these responses 
. I was trying to write a module for testing that simulates the instrument/3 macro in Phoenix.Endpoint.Instrument so I can test my instrumenters. The macro should produce the following code:
def instrument(:my_event, compile, runtime, fun) do
result = MyModule.my_event(:start, compile, runtime)
start = :erlang.monotonic_time()
try do
fun.()
after
diff = :erlang.monotonic_time() - start
MyModule.my_event(:stop, diff, result)
end
end
