Block that outputs how often the trigger input changed to true
since the last invocation of reset.
This block may be used as a counter. Its output y starts
at the parameter value y_start.
Whenever the input signal trigger changes to true,
the output is incremented by 1.
When the input reset changes to true,
then the output is reset to y = y_start.
If both inputs trigger and reset change
simultaneously, then the ouput is y = y_start.
visible attribute in icon.