Running Sphinx v2.2.2

Exception occurred:
  File "/w/workspace/rtdv3-global-verify-master/docs/.tox/docs/lib/python3.6/site-packages/blockdiag/parser.py", line 42, in <module>
    from funcparserlib.lexer import LexerError, Token, make_tokenizer
  File "/w/workspace/rtdv3-global-verify-master/docs/.tox/docs/lib/python3.6/site-packages/funcparserlib/lexer.py", line 80
    def match_specs(specs, str, i, (line, pos)):
                                   ^
SyntaxError: invalid syntax
The full traceback has been saved in /tmp/sphinx-err-5iur0ufl.log, if you want to report the issue to the developers.
Please also report this if it was a user error, so that a better error message can be provided next time.
A bug report can be filed in the tracker at <https://github.com/sphinx-doc/sphinx/issues>. Thanks!
ERROR: InvocationError for command /w/workspace/rtdv3-global-verify-master/docs/.tox/docs/bin/sphinx-build -b html -n -d /w/workspace/rtdv3-global-verify-master/docs/.tox/docs/tmp/doctrees ./ /w/workspace/rtdv3-global-verify-master/docs/_build/html (exited with code 2)
ERROR: invocation failed (exit code 1)
✖ FAIL docs in 37.174 seconds
___________________________________ summary ____________________________________
ERROR:   docs: parallel child exit code 1