TODO #
Rename
exp_map_circle
→circle.exp
coe_inv_circle_eq_conj
→circle.coe_inv_eq_conj
coe_div_circle
→circle.coe_div
+norm_cast
@[simp]
Rename
exp_map_circle
→ circle.exp
coe_inv_circle_eq_conj
→ circle.coe_inv_eq_conj
coe_div_circle
→ circle.coe_div
+ norm_cast