code: def get_keybinding(self, mode, key):
          
          cmdline = None
          bindings = self._bindings
          if key in bindings.scalars:
              cmdline = bindings[key]
          if mode in bindings.sections:
              if key in bindings[mode].scalars:
                  value = bindings[mode][key]
                  if value:
                      cmdline = value
                  else:
                      # to be sure it isn't mapped globally
                      cmdline = None
          # Workaround for ConfigObj misbehaviour. cf issue #500
          # this ensures that we get at least strings only as commandlines
          if isinstance(cmdline, list):
              cmdline = ','.join(cmdline)
          return cmdline
docs: look up keybinding from `MODE-maps` sections
  
          :param mode: mode identifier
          :type mode: str
          :param key: urwid-style key identifier
          :type key: str
          :returns: a command line to be applied upon keypress
          :rtype: str