code: func (nm *nmVertex) approximatelyEqualToVertex(other *nmVertex) bool {
  	return math.Abs(nm.result-other.result) < 2*delta
  }
docs: // approximatelyEqualToVertex returns a bool indicating if the
  // *result* of this vertex is approximately equal to the vertex
  // provided.  Approximately is 2 * delta as the algorithm may
  // cease within a delta distance of the true value, so we may
  // end up with a result that's 2*delta away if we came from
  // the other direction.