docs: def insert(self, lines=None):
          """
          Insert lines into the editor.
  
          Note:
              To insert before the first line, use :func:`~exa.core.editor.Editor.preappend`
              (or key 0); to insert after the last line use :func:`~exa.core.editor.Editor.append`.
  
          Args:
              lines (dict): Dictionary of lines of form (lineno, string) pairs
          """
          for i, (key, line) in enumerate(lines.items()):
              n = key + i
              first_half = self._lines[:n]
              last_half = self._lines[n:]
              self._lines = first_half + [line] + last_half