Correct add at so that if the collection is empty, at will be ignored. Remove the model only if it exists on the collection. Remove signal arg from replace method. Correct replace so that it only replaces if the oldModel exists while the newModel does not.
Correct add at so that if the collection is empty, at will be ignored. Remove the model only if it exists on the collection. Remove signal arg from replace method. Correct replace so that it only replaces if the oldModel exists while the newModel does not.

GCheung55/Neuro,GCheung55/Neuro