--- a/Pipfile
+++ b/Pipfile
@@ -3,11 +3,12 @@ url = "https://pypi.org/simple"
 verify_ssl = true
 name = "pypi"
 
 [dev-packages]
 
 [packages]
 pipenv = "==2018.5.18"
 virtualenv = "==15.2.0"
+six = "==1.10.0"
 
 [requires]
 python_version = "2.7"

--- a/Pipfile.lock
+++ b/Pipfile.lock
@@ -1,12 +1,12 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "bad1afe9071c33c7547e277c2ce4817e2c20e4039bccfc4e62595f30eb637f98"
+            "sha256": "925379349ecc7ddfa287a6618896f4d97bf387a3bb6c5ef182bd04714dbd640c"
         },
         "pipfile-spec": 6,
         "requires": {
             "python_version": "2.7"
         },
         "sources": [
             {
                 "name": "pypi",
@@ -26,16 +26,24 @@
         "pipenv": {
             "hashes": [
                 "sha256:04b9a8b02a3ff12a5502b335850cfdb192adcfd1d6bbdb7a7c47cae9ab9ddece",
                 "sha256:e96d5bfa6822a17b2200d455aa5f9002c14361c50df1b1e51921479d7c09e741"
             ],
             "index": "pypi",
             "version": "==2018.5.18"
         },
+        "six": {
+            "hashes": [
+                "sha256:0ff78c403d9bccf5a425a6d31a12aa6b47f1c21ca4dc2573a7e2f32a97335eb1",
+                "sha256:105f8d68616f8248e24bf0e9372ef04d3cc10104f1980f54d57b2ce73a5ad56a"
+            ],
+            "index": "pypi",
+            "version": "==1.10.0"
+        },
         "virtualenv": {
             "hashes": [
                 "sha256:1d7e241b431e7afce47e77f8843a276f652699d1fa4f93b9d8ce0076fd7b0b54",
                 "sha256:e8e05d4714a1c51a2f5921e62f547fcb0f713ebbe959e0a7f585cc8bef71d11f"
             ],
             "index": "pypi",
             "version": "==15.2.0"
         },