add limited python2 compatibility (#13)

codefresh.yml

@@ -12,3 +12,4 @@ steps:
     commands:
       - flake8
       - python setup.py test
+      - python2 setup.py test
\ No newline at end of file

tests/test_data.py

-import torchani
-import unittest
-import tempfile
-import os
-import torch
-import torchani.pyanitools as pyanitools
-import torchani.data
-from math import ceil
-from bisect import bisect
-from pickle import dump, load
+import sys
 
+if sys.version_info.major >= 3:
+    import torchani
+    import unittest
+    import tempfile
+    import os
+    import torch
+    import torchani.pyanitools as pyanitools
+    import torchani.data
+    from math import ceil
+    from bisect import bisect
+    from pickle import dump, load
 
-path = os.path.dirname(os.path.realpath(__file__))
-dataset_dir = os.path.join(path, 'dataset')
+    path = os.path.dirname(os.path.realpath(__file__))
+    dataset_dir = os.path.join(path, 'dataset')
 
-
-class TestDataset(unittest.TestCase):
+    class TestDataset(unittest.TestCase):
 
         def setUp(self, data_path=dataset_dir):
             self.data_path = data_path
@@ -158,6 +159,5 @@ class TestDataset(unittest.TestCase):
                 e2 = i2[2].item()
                 self.assertEqual(e1, e2)
 
-
-if __name__ == '__main__':
+    if __name__ == '__main__':
         unittest.main()