Three Echoes

Contract three_echoes. Extends Contract with:

.broadcast

The intercepted broadcast: three frequency fragments.

Returns: ThreeEchoesBroadcast

ThreeEchoesBroadcast

Member	Returns	Meaning
.freq_a	string	The 1st, 4th, 7th… (every third) characters of the original signal, in order
.freq_b	string	The 2nd, 5th, 8th… characters
.freq_c	string	The 3rd, 6th, 9th… characters

Approach: re-interleave the three fragments round-robin (a, b, c, a, b, c…) to rebuild the original signal, then transmit it.