docs: def safe_cpp_var(s):
      """
      Given a string representing a variable, return a new string that is safe
      for C++ codegen. If string is already safe, will leave it alone.
      """
      s = str(s)
      # Remove non-word, non-space characters
      s = re.sub(r"[^\w\s]", '', s)
      # Replace spaces with _
      s = re.sub(r"\s+", '_', s)
      # Prefix with underscore if what is left is a reserved word
      s = "_" + s if s in CPP_KEYWORDS or s[0].isdigit() else s
      return s