code: private final boolean is_2_single_quotes_helper() throws IOException
      {
          int c = read_char();
          if (c != '\'') {
              unread_char(c);
              return false;
          }
          c = read_char();
          if (c != '\'') {
              unread_char(c);
              unread_char('\'');
              return false;
          }
          return true;
      }
docs: this peeks ahead to see if the next two characters
  are single quotes. this would finish off a triple
  quote when the first quote has been read.
  if it succeeds it "consumes" the two quotes
  it reads.
  if it fails it unreads
  @return true if the next two characters are single quotes
  @throws IOException