docs: def kill(self, container_id=None, sudo=None, signal=None):
  
      ''' stop (kill) a started OciImage container, if it exists
  
          Equivalent command line example:      
             singularity oci kill <container_ID>
             
          Parameters
          ==========
          container_id: the id to stop.
          signal: signal sent to the container (default SIGTERM)
          sudo: Add sudo to the command. If the container was created by root,
                you need sudo to interact and get its state.
  
          Returns
          =======
          return_code: the return code to indicate if the container was killed.
      '''
      sudo = self._get_sudo(sudo)
      container_id = self.get_container_id(container_id)
  
      # singularity oci state
      cmd = self._init_command('kill')
  
      # Finally, add the container_id
      cmd.append(container_id)
  
      # Add the signal, if defined
      if signal != None:
          cmd = cmd + ['--signal', signal]
  
      # Run the command, return return code
      return self._run_and_return(cmd, sudo)