simp only [natCast_log, neg_mul]
case convert_2
N : ℕ
z : ℂ
z_ne_zero : z ≠ 0
⊢ HasDerivAt (fun z => -↑N ^ z) (-↑N ^ z * ↑(↑N).log) z
case convert_2
N : ℕ
z : ℂ
z_ne_zero : z ≠ 0
⊢ HasDerivAt (fun z => -↑N ^ z) (-(↑N ^ z * (↑N).log)) z