diff --git a/Lib/test/test_tokenize.py b/Lib/test/test_tokenize.py
@@ -1,7 +1,7 @@
from test import support
from tokenize import (tokenize, _tokenize, untokenize, NUMBER, NAME, OP,
                     STRING, ENDMARKER, ENCODING, tok_name, detect_encoding,
-                     open as tokenize_open, Untokenizer)
from io import BytesIO
from unittest import TestCase, mock
from test.test_grammar import (VALID_UNDERSCORE_LITERALS,
@@ -1351,6 +1351,28 @@ def assertExactTypeEqual(self, opstr, *optypes):
        self.assertEqual(tok_name[tokens[1 + num_optypes].exact_type],
                         tok_name[token.ENDMARKER])

    def test_exact_type(self):
        self.assertExactTypeEqual('()', token.LPAR, token.RPAR)
        self.assertExactTypeEqual('[]', token.LSQB, token.RSQB)

diff --git a/Lib/token.py b/Lib/token.py
@@ -129,33 +129,37 @@ def _main():
                comment = comment_match.group(1)
                tokens[prev_val]['comment'] = comment
    keys = sorted(tokens.keys())
-    # load the output skeleton from the target:
    try:
-        fp = open(outFileName)
    except OSError as err:
        sys.stderr.write("I/O error: %s\n" % str(err))
        sys.exit(2)
    with fp:
-        format = fp.read().split("\n")
    try:
-        start = format.index("#--start constants--") + 1
-        end = format.index("#--end constants--")
    except ValueError:
        sys.stderr.write("target does not contain format markers")
        sys.exit(3)
    lines = []
    for key in keys:
-        lines.append("%s = %d" % (tokens[key]["token"], key))
        if "comment" in tokens[key]:
-            lines.append("# %s" % tokens[key]["comment"])
    format[start:end] = lines
    try:
-        fp = open(outFileName, 'w')
    except OSError as err:
        sys.stderr.write("I/O error: %s\n" % str(err))
        sys.exit(4)
    with fp:
-        fp.write("\n".join(format))


if __name__ == "__main__":