∀ {k : Type u_1} {G : Type u_2} [inst : Monoid G] [inst_1 : Semiring k] [inst_2 : MulSemiringAction G k]
  (f : SkewMonoidAlgebra k G), f ∈ Submodule.span k (⇑(SkewMonoidAlgebra.of k G) '' ↑f.support)