private fun Demand.demand_getLookupKey(cityPairHash: Hash160, nowTime: Int): ByteArray (source)
Gets the key used to store the demand for tracking lookup. Tracking requires knowledge of the "identifier" and city pair.
cityPairHash - the ripemd160 hash of: script hash (hex) (salt) + origin city + destination city (ascii)
Return
the lookup key for use with Storage