code: public static String fill(char c, int size) {
          StringBuilder builder = new StringBuilder();
          for (int i = 0; i < size; i++) {
              builder.append(c);
          }
          return builder.toString();
      }
docs: Creates a new String filled with size of a repeating character
  
  @param c Character to repeat
  @param size Size of resulting String
  @return String full of repeated characters