offer_coin defines the coin being offered (i.e. 1000000uluna).
ask_denom defines the denom of the coin to swap to.
QuerySwapResponse is the response type for the Query/Swap RPC method.
GET //terra/market/v1beta1/swap HTTP/1.1 Host: lunc.nownodes.io Accept: */*
A successful response.
{ "return_coin": { "denom": "text", "amount": "text" } }