### Question:
TeamHelper { public static String baseTeamKey(@Nullable String teamKey) { if (validateMultiTeamKey(teamKey)) { return teamKey.substring(0, teamKey.length() - 1); } return teamKey; } private  TeamHelper(); static boolean validateTeamKey(@Nullable String key); static boolean validateMultiTeamKey(@Nullable String key); static String baseTeamKey(@Nullable String teamKey); static int getTeamNumber(@Nullable String key);  }### Answer:
@Test public void testBaseTeamKey() { assertEquals("frc432", TeamHelper.baseTeamKey("frc432")); assertEquals("frc432", TeamHelper.baseTeamKey("frc432B")); assertEquals("", TeamHelper.baseTeamKey("")); assertNull(TeamHelper.baseTeamKey(null)); }