Having trouble with example formatter about format_lean

[kbuzzard]

Progress: trying from a different directory.

format_lean/src$ ipython3
Python 3.6.7 (default, Oct 22 2018, 11:32:17)     <--- GAARGH
...
In [1]: from format_lean.lecture import render_lean_file
   ...: 
---------------------------------------------------------------------------
ModuleNotFoundError                       Traceback (most recent call last)
<ipython-input-1-662f8a35540b> in <module>()
----> 1 from format_lean.lecture import render_lean_file

/home/buzzard/Encfs/Computer_languages/python/format_lean/src/format_lean/lecture.py in <module>()
      1 #!/usr/bin/env python3
      2 from typing import List
----> 3 from dataclasses import dataclass, field
      4 import distutils
      5 from pathlib import Path

ModuleNotFoundError: No module named 'dataclasses'

So my issue is that I'm not using 3.7 after all :-(