History-only sensitive anomaly

• Adding gget --- identical to get except that it cannot be invoked after put.

  bbufh = interface {empty,mid,midput,full,fullput}
      extends bbuf { mid } becomes { mid, midput }
                   { full } becomes { full, fullput }
    gget = method({mid,full}b:self{mid,empty}) replies(int)
  end bbufh
  bbufhi = class implements bbufh extends bbuf_basei
    after get{mid} use {mid}, put{mid} use {midput}, put{full} use {fullput}
    gget = method({mid,full}b:self{mid,empty}) replies(int)
      reply(b!get())
    end gget
  end bbufhi