code: def select(max_staleness, selection):
      
      if max_staleness == -1:
          return selection
  
      # Server Selection Spec: If the TopologyType is ReplicaSetWithPrimary or
      # ReplicaSetNoPrimary, a client MUST raise an error if maxStaleness <
      # heartbeatFrequency + IDLE_WRITE_PERIOD, or if maxStaleness < 90.
      _validate_max_staleness(max_staleness, selection.heartbeat_frequency)
  
      if selection.primary:
          return _with_primary(max_staleness, selection)
      else:
          return _no_primary(max_staleness, selection)
docs: Apply max_staleness, in seconds, to a Selection.