package Ġru . pop ov . body a . how money . data . database . dao Ċ Ċ import Ġandroid . arch . persistence . room . Dao Ċ import Ġandroid . arch . persistence . room . Query Ċ import Ġio . reactivex . Single Ċ import Ġru . pop ov . body a . how money . domain . wallet . models . Currency Ċ import Ġru . pop ov . body a . how money . domain . wallet . models . Exchange Rate Ċ Ċ @ Dao Ċ interface ĠExchange Rate Dao Ġ: ĠBase Dao < Exchange Rate > Ġ{ ĊĠĠĠ Ġ@ Query (" SELECT Ġrate ĠFROM Ġexchange _ rates ĠWHERE Ġfrom Currency =: from Currency ĠAND Ġto Currency =: to Currency ") ĊĠĠĠ Ġfun Ġget Exchange Rate ( from Currency : ĠCurrency , Ġto Currency : ĠCurrency ): ĠSingle < Double > Ċ }