def _service_time(self, ast):
     # ast is the average service time
     # Service times are also exponential, with parameter 1/ast
     return expdistr(1 / float(ast))
 def _inter_arrival_time(self, mar):
     # mar is the mean arrival time
     # Inter-arrival time is exponential, with parameter 1/mar
     return expdistr(1 / float(mar))