code: def parse_hl_lines(expr: str) -> list[int]:
      """Support our syntax for emphasizing certain lines of code.
  
      `expr` should be like '1 2' to emphasize lines 1 and 2 of a code block.
      Returns a list of integers, the line numbers to emphasize.
      """
      if not expr:
          return []
  
      try:
          return list(map(int, expr.split()))
      except ValueError:  # pragma: no cover
          return []
  
file_path: markdown/markdown/extensions/codehilite.py
imports: from __future__ import annotations
  from .None import Extension
  from ..treeprocessors import Treeprocessor
  from ..util import parseBoolValue
  from typing import TYPE_CHECKING, Callable, Any
label_desc: Use image node_id 1 for calling a global function with example usage: parse_hl_lines(expr) and returns: list, list, list