code: func (pdfa *ParametricDFA) isPrefixSink(state ParametricState, queryLen uint32) bool {
  	if state.isDeadEnd() {
  		return true
  	}
  
  	remOffset := queryLen - state.offset
  	if remOffset < pdfa.diameter {
  		stateDistances := pdfa.distance[pdfa.diameter*state.shapeID:]
  		prefixDistance := stateDistances[remOffset]
  		if prefixDistance > pdfa.maxDistance {
  			return false
  		}
  
  		for _, d := range stateDistances {
  			if d < prefixDistance {
  				return false
  			}
  		}
  		return true
  	}
  	return false
  }
docs: // Returns true iff whatever characters come afterward,
  // we will never reach a shorter distance