This sort of thing normally happens your python3 or pip3 has been updated, because you have to in order to use pip, but the newer pip now breaks compatibility with your old python (3.5 in this case).
There are a few solutions, the easiest is perhaps to upgrade to a newer OS with a newer distro provided Python 3 or to manually install a newer version of Python/OR use a PPA like deadsnakes that provides newer versions.
Traceback (most recent call last):
File "/usr/bin/pip3", line 11, in
File "/usr/local/lib/python3.5/dist-packages/pip/__init__.py", line 11, in main
from pip._internal.utils.entrypoints import _wrapper
File "/usr/local/lib/python3.5/dist-packages/pip/_internal/utils/entrypoints.py", line 12
SyntaxError: invalid syntax
python, ubuntu, linux, syntaxerror, invalid, syntax, pip, sys, version_info, updated, newer, compatibility, solutions, easiest, upgrade, os, distro, provided, manually, install, essentially, traceback, quot, usr, bin, lib, dist, packages, __init__, py, _internal, utils, entrypoints, import, _wrapper,