Durrant (2015, doi: chpz): Valence electron equivalent γ ... "the formal shared electron count at a given atom, obtained by any combination of valid ionic and covalent resonance forms that reproduces the observed charge distribution" .... "If γ(X) > 8, neither form of the octet rule is obeyed and the atom is hypervalent".
Diazomethane is hypervalent: γ(N) = 10 CLi6 is hypervalent: γ(C) = 10