Fix double quotes

Author: lpozo

python-doctest/calculations/test_calculations.py

@@ -0,0 +1,14 @@
+import doctest
+import unittest
+
+import calculations
+
+
+def load_tests(loader, tests, ignore):
+    tests.addTests(doctest.DocFileSuite("tests_file.txt"))
+    tests.addTests(doctest.DocTestSuite(calculations))
+    return tests
+
+
+if __name__ == "__main__":
+    unittest.main()