def _pre_run(self, pre_run=None):
        " Called during `run`. "
        if pre_run:
            pre_run()

        # Process registered "pre_run_callables" and clear list.
        for c in self.pre_run_callables:
            c()
        del self.pre_run_callables[:]
def _pre_run ( self , pre_run = None ) : if pre_run : pre_run ( ) for c in self . pre_run_callables : c ( ) del self . pre_run_callables [ : ]
Called during `run`.