code: def escape_code_start(source, ext, language="python"):
      """Escape code start with '# '"""
      parser = StringParser(language)
      for pos, line in enumerate(source):
          if not parser.is_quoted() and is_escaped_code_start(
              line, ext
          ):
              source[pos] = (
                  _SCRIPT_EXTENSIONS.get(ext, {}).get("comment", "#")
                  + " "
                  + line
              )
          parser.read_line(line)
      return source
  
file_path: jupytext/src/jupytext/magics.py
imports: import re
  from .languages import _COMMENT, _SCRIPT_EXTENSIONS, usual_language_name
  from .stringparser import StringParser
label_desc: Use image node_id 8 for calling a global function with example usage: escape_code_start(source, ext, language) and returns: source