Adding a New Operator to CPython 3.9 Fails to Recognize Syntax in Python

I'm following the CPython internals guide from Chapter 7.5 on adding an operator. The guide uses the example of the "almost equal" operator (~=). Despite following the prescribed steps and additional troubleshooting, the implementation does not work as expected. Here's a detailed breakdown of what I've done after successfully installing and building the CPython project:

1. Grammar File Changes:

   • Updated Grammar/Grammar on line 141 to include ~=:

     comp_op: '<'|'>'|'=='|'>='|'<='|'<>'|'!='|'in'|'not' 'in'|'is'|'is' 'not'|'~='
     

   • Modified Grammar/python.gram on line 413 by adding | ale_bitwise_or under the compare_op_bitwise_or_pair[CmpopExprPair*] section.
   • On line 425, added a new rule:

     ale_bitwise_or[CmpopExprPair*]: '~=' a=bitwise_or { _PyPegen_cmpop_expr_pair(p, AlE, a) }
     

2. Token Definitions:

   • Added TILDEEQUAL '~=' to Grammar/Tokens on line 56.

3. AST Definitions:

   • Updated Parser/Python.asdl on line 102 to include AlE:

     cmpop = Eq | NotEq | Lt | LtE | Gt | GtE | Is | IsNot | In | NotIn | AlE
     

4. Manual Code Additions:

   • Expected automatic updates to /Parser/token.c did not occur, so I manually added:

     case '~':
         switch (c2) {
             case '=': return TILDEEQUAL;
         }
     break;
     

   • Defined TILDEEQUAL in token.h after it was not found.

After rebuilding the project multiple times and even re-cloning, I continue to receive a syntax error when running the following Python code:

import ast
ast.parse("1 ~= 1")
1 ~= 1

The error is:

SyntaxError: invalid syntax

I'm using Visual Studio for building the project solution, editing in VSCode, and running /PCbuild/build.bat --regen from the VSCode terminal. My environment is Python 3.9.19+ (heads/3.9-dirty:40d77b9367) on a 64-bit debug build.

Question:

1. What might I be missing in the process that prevents Python from recognizing the new ~= operator syntax?