docs: def next_instruction_is_function_or_class(lines):
      """Is the first non-empty, non-commented line of the cell either a function or a class?"""
      for i, line in enumerate(lines):
          if not line.strip():  # empty line
              if i > 0 and not lines[i - 1].strip():
                  return False
              continue
          if line.startswith('def ') or line.startswith('class '):
              return True
          if line.startswith(('#', '@', ' ')):
              continue
          return False
  
      return False