code: public static <K, V> TypeChecker<Map<? extends K, ? extends V>> tMap(Class<? extends K> keyType, TypeChecker<? extends V> valueChecker) {
          return tMap(tSimple(keyType), valueChecker);
      }
docs: Creates a recursing type checker for a {@link java.util.Map}.
  
  @param keyType The class to check the keys against
  @param valueChecker The typechecker to check the values with
  @return a typechecker for a Map containing keys of the specified type and values passing the specified type checker