code: public String form( String s ) {
          if (fmt != 's') {
              throw new java.lang.IllegalArgumentException();
          }
          if (precision >= 0 && precision < s.length()) {
              s = s.substring(0, precision);
          }
  
          return pad(s);
      }
docs: Formats a string into a larger string (like sprintf in C)
  
  @param s      the value to format
  
  @return the formatted string