Installing backshift via pip (below are three methods; pick one of the three):

• For CPython 3.x (slow, but should work fine):
  1. python3 -m virtualenv ~/backshift
  2. source ~/backshift/bin/activate
  3. python3 -m pip install backshift
• For CPython 3.x plus a little Cython for speed:
  1. python3 -m virtualenv ~/backshift
  2. source ~/backshift/bin/activate
  3. python3 -m pip install backshift pyx-treap rolling-checksum-pyx-mod
• For Pypy3 (fast without the Cython - in fact it might be slower with the cython):
  1. pypy3 -m virtualenv ~/backshift
  2. source ~/backshift/bin/activate
  3. pypy3 -m pip install backshift