addMolecule<T> method Null safety

Molecule<T>? addMolecule<T>(
  1. Molecule<T> molecule

Adds a Molecule to the store. molecule the Molecule to be added to the store.

Returns the Molecule added to the store if no Molecule with the same key exists, otherwise returns null.


Molecule<T>? addMolecule<T>(Molecule<T> molecule) {
  if (_molecules.containsKey(molecule.key)) {
    return null;

  return _molecules.putIfAbsent(molecule.key, () => molecule) as Molecule<T>;