Formatter moves `in` into comments

[chandradeepdey]

DY* code

let (idx_sess_b, idx_s2msg2) = responder_send_msg_2 bob idx_s2msg1 in
// (3) + (4)
let idx_s1msg3 = initiator_send_msg_3 alice idx_sess_a idx_s2msg2 in
// (5)

gets rewritten as

let (idx_sess_b, idx_s2msg2) = responder_send_msg_2 bob idx_s2msg1 // (3) + (4) in
let idx_s1msg3 = initiator_send_msg_3 alice idx_sess_a idx_s2msg2 // (5) in