Cannot import in python 3.7

[Neradoc]

>>> import adafruit_rfm9x
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/pi/circuit/venv/lib/python3.7/site-packages/adafruit_rfm9x.py", line 142, in <module>
    class RFM9x:
  File "/home/pi/circuit/venv/lib/python3.7/site-packages/adafruit_rfm9x.py", line 265, in RFM9x
    crc: bool = True
NameError: name 'SPI' is not defined

The real exception, hidden by the typing try-except is the following:

  File "/home/pi/circuit/venv/lib/python3.7/site-packages/adafruit_rfm9x.py", line 31, in <module>
    from typing import Optional, Type, Literal
ImportError: cannot import name 'Literal' from 'typing' (/usr/lib/python3.7/typing.py)

Literal is in python 3.8.