code: def _index_to_row_col(lines, index):
      r
      if index < 0:
          raise IndexError('negative index')
      current_index = 0
      for line_number, line in enumerate(lines):
          line_length = len(line)
          if current_index + line_length > index:
              return line_number, index - current_index
          current_index += line_length
      raise IndexError('index %d out of range' % index)
docs: r"""
      >>> lines = ['hello\n', 'world\n']
      >>> _index_to_row_col(lines, 0)
      (0, 0)
      >>> _index_to_row_col(lines, 7)
      (1, 1)