### Question:
PairUtils { @NonNull public static String localToServer(@NonNull String pair) { return pair.replace(LOCAL_PAIR_DELIMITER, SERVER_PAIR_DELIMITER).toLowerCase(Locale.US); } private  PairUtils(); @NonNull static String localToServer(@NonNull String pair); @NonNull static String serverToLocal(@NonNull String pair); static boolean isSupportedPair(@NonNull Context context, @NonNull String pair); @NonNull static Set<String> exchangePairs(@NonNull ExchangeInfo exchangeInfo); @NonNull static Map<String, BigDecimal> filterForNonZero(
            @NonNull Map<String, BigDecimal> funds); static final Comparator<String> CURRENCY_COMPARATOR; }### Answer:
@Test public void localToServer() throws Exception { assertEquals("btc_usd", PairUtils.localToServer("BTC/USD")); }