fix: Update for running with Python v3.9 or higher and corrections of documentation and minor inconsistencies

Author: hpdekoning

tool-support/bnf_grammar_tools/README.adoc

@@ -22,7 +22,7 @@ Instructions on how to export a selected version of the specification from View
 
 === Install the Python Environment
 
-Ensure that Python version 3.8 or higher is installed on your machine. The most convenient way is to use the https://www.jetbrains.com/pycharm/[PyCharm] tool. Create a dedicated `conda` or `venv` development environment and activate it. The best tool to install a Python base environment is https://github.com/conda-forge/miniforge[miniforge].
+Ensure that Python version 3.9 or higher is installed on your machine. The most convenient way is to use the https://www.jetbrains.com/pycharm/[PyCharm] tool. Create a dedicated `conda` or `venv` development environment and activate it. The best tool to install a Python base environment is https://github.com/conda-forge/miniforge[miniforge].
 
 After installation check the active Python version, e.g.:
 
@@ -35,6 +35,7 @@ After installation check the active Python version, e.g.:
 Also ensure that the latest version of the following packages are installed. You can use `pip` or `conda` or `mamba`.
 
 * Package https://pypi.org/project/beautifulsoup4/[beautifulsoup4] is used to parse the HTML input file.
+* Package https://pypi.org/project/lxml/[lxml] is used to assist beautifulsoup4 with processing SVG/XML files.
 * Package https://pypi.org/project/lark/[lark] is used to parse and verify the extracted BNF source.
 * Package https://pypi.org/project/pytest/[pytest] is used to run unit tests.
 
@@ -43,6 +44,7 @@ for example with the following commands:
 [source,shell]
 ----
     $ pip install beautifulsoup4
+    $ pip install lxml
     $ pip install lark
     $ pip install pytest
 ----

tool-support/bnf_grammar_tools/bnf_grammar/bnf_grammar_processor.py

@@ -12,8 +12,9 @@
 @author: Hans Peter de Koning (DEKonsult)
 
 Requirements:
-This tool requires installation of the following packages:
+This tool requires Python v3.9 or higher and installation of the following packages:
 - beautifulsoup4 (See https://pypi.org/project/beautifulsoup4/)
+- lxml (See https://pypi.org/project/lxml/)
 - lark (See https://pypi.org/project/lark)
 """
 
@@ -28,12 +29,11 @@
 from enum import Enum, auto
 from logging import Logger
 from textwrap import wrap
-from types import NoneType
 from typing import Any, ClassVar, Iterable, Optional
 
-from bs4 import BeautifulSoup, Tag, PageElement, NavigableString
+from bs4 import BeautifulSoup, Tag, PageElement
 
-from lark import Lark, Transformer, Tree, UnexpectedInput
+from lark import Lark, UnexpectedInput
 
 # Create logger for diagnostic messages at debug, info, warning, error and critical levels
 import logging
@@ -661,7 +661,7 @@ def extract_bnf_from_spec(self, input_dir: str, output_dir: str, input_file: str
             elif tag.name == "ol" and inside_bnf_clause and contains_pre_tag and tag.parent.name != "li":
                 LOGGER.debug(f"note <ol> tag={tag}")
                 list_item_count = 0
-                note_list = NoteList(clause_id, [], [])
+                note_list = NoteList(clause_id, [], "")
 
                 # Update the contents of <ol> within the HTML tree
                 self.cleanup_note_html(tag)
@@ -1225,7 +1225,7 @@ def is_lower_kebab_case(text: str) -> bool:
 
 def render_nested_lists(html_snippet: str, mode: RenderMode, apply_line_comment: bool) -> str:
     """
-    Return
+    Return nested note lists, rendered as comments in HTML or TXT format.
 
     :param html_snippet: string in HTML format that contains nested ol and/or ul lists
     :param mode: output render mode
@@ -1386,6 +1386,7 @@ def main() -> None:
     args = parser.parse_args()
     LOGGER.debug(f"args={args}")
     LOGGER.debug(f"bnf_grammar_processor started in {os.getcwd()}")
+    LOGGER.info(f"Running Python {sys.version}")
 
     input_dir = args.input_dir
     output_dir = args.output_dir