code: func (m *txSortedMap) Ready(start uint64) types.Transactions {
  	// Short circuit if no transactions are available
  	if m.index.Len() == 0 || (*m.index)[0] > start {
  		return nil
  	}
  	// Otherwise start accumulating incremental transactions
  	var ready types.Transactions
  	for next := (*m.index)[0]; m.index.Len() > 0 && (*m.index)[0] == next; next++ {
  		ready = append(ready, m.items[next])
  		delete(m.items, next)
  		heap.Pop(m.index)
  	}
  	m.cache = nil
  
  	return ready
  }
docs: // Ready retrieves a sequentially increasing list of transactions starting at the
  // provided nonce that is ready for processing. The returned transactions will be
  // removed from the list.
  //
  // Note, all transactions with nonces lower than start will also be returned to
  // prevent getting into and invalid state. This is not something that should ever
  // happen but better to be self correcting than failing!