title: CPython 3.9 python.gram file - Error when trying to run make regen-pegen with utf-8 text
body: <p>I'm trying to create a custom Python version, with the ability to write the keywords in Hebrew.
  I cloned CPython, and I tried to edit the <code>python.gram</code> file, in order to accept also Hebrew keywords.
  for example, in the <code>for</code> keyword, I tried to do that:
  Instead of:</p>
  <pre><code>for_stmt[stmt_ty]:
  | 'for' t=star_targets 'in' ~ ex=star_expressions ':' tc=[TYPE_COMMENT] b=block el=[else_block] {
      _Py_For(t, ex, b, el, NEW_TYPE_COMMENT(p, tc), EXTRA) }
  </code></pre>
  <p>I tried to write:</p>
  <pre><code>for_stmt[stmt_ty]:
  | ('עבור' | 'for') t=star_targets 'in' ~ ex=star_expressions ':' tc=[TYPE_COMMENT] b=block el=[else_block] {
      _Py_For(t, ex, b, el, NEW_TYPE_COMMENT(p, tc), EXTRA) }
  </code></pre>
  <p>But when I try to run <code>make regen-pegen</code> again, I get this error:
  <code>AssertionError: 'עבור' is not a known literal</code></p>
  <p>There is something to do? Or utf-8 is not supported?</p>
  <p>Thank's!</p>