code: def run_context(self):
          
          with LiveExecution.lock:
              if self.edited_source is None:
                  yield True, self.known_good, self.ns
                  return
  
              ns_snapshot = copy.copy(self.ns)
              try:
                  yield False, self.edited_source, self.ns
                  self.known_good = self.edited_source
                  self.edited_source = None
                  self.call_good_cb()
                  return
              except Exception as ex:
                  tb = traceback.format_exc()
                  self.call_bad_cb(tb)
                  self.edited_source = None
                  self.ns.clear()
                  self.ns.update(ns_snapshot)
docs: Context in which the user can run the source in a custom manner.
  
          If no exceptions occur then the source will move from 'tenuous'
          to 'known good'.
  
          >>> with run_context() as (known_good, source, ns):
          >>> ...  exec source in ns
          >>> ...  ns['draw']()