An exact proof term for the current goal is CD_mul_1L {3} CSNo quaternion_tag_fresh minus_CSNo conj_CSNo add_CSNo mul_CSNo CSNo_0 CSNo_1 CSNo_conj_CSNo minus_CSNo_0 add_CSNo_0R mul_CSNo_0L mul_CSNo_0R mul_CSNo_1L mul_CSNo_1R.