Use pathlib2 for ancient Python versions

Author: maresb

packages/python/plotly/plotly/io/_kaleido.py

@@ -1,11 +1,18 @@
 from __future__ import absolute_import
 from six import string_types
 import os
-from pathlib import Path, PurePath
+
+
 import json
 import plotly
 from plotly.io._utils import validate_coerce_fig_to_dict
 
+try:
+    from pathlib import Path, PurePath
+except ImportError:
+    # For Python < 3.4 use pathlib2
+    from pathlib2 import Path, PurePath
+
 try:
     from kaleido.scopes.plotly import PlotlyScope
 

packages/python/plotly/requirements.txt

@@ -10,3 +10,6 @@ six==1.8.0
 
 ## retrying requests ##
 retrying==1.3.3
+
+## Allow pathlib2 as pathlib substitute for old Python versions ##
+pathlib2;python_version<"3.4"

packages/python/plotly/setup.py

@@ -505,7 +505,7 @@ def run(self):
         ),
         ("etc/jupyter/nbconfig/notebook.d", ["plotlywidget.json"]),
     ],
-    install_requires=["retrying>=1.3.3", "six"],
+    install_requires=["retrying>=1.3.3", "six", 'pathlib2;python_version<"3.4"'],
     zip_safe=False,
     cmdclass=dict(
         build_py=js_prerelease(versioneer_cmds["build_py"]),