Remove six dependency (#5)

Remove six dependency

Author: Ryan Munro

.travis.yml

@@ -2,6 +2,11 @@ language: python
 os:
     - "linux"
 env:
+    - NODE_VERSION="7.5"
+    - NODE_VERSION="7.3"
+    - NODE_VERSION="7.2"
+    - NODE_VERSION="7.1"
+    - NODE_VERSION="7.0"
     - NODE_VERSION="6.1"
     - NODE_VERSION="6.0"
     - NODE_VERSION="5.11"
@@ -35,7 +40,6 @@ before_install:
     - source ~/.nvm/nvm.sh
     - nvm install $NODE_VERSION
 install:
-    - pip install six
     - npm install
 before_script:
     - python -V

node_python_bridge.py

@@ -1,12 +1,12 @@
 from __future__ import unicode_literals
 
-import six
 import os
 import sys
 import json
 import traceback
 
 NODE_CHANNEL_FD = int(os.environ['NODE_CHANNEL_FD'])
+UNICODE_TYPE = unicode if sys.version_info[0] == 2 else str
 
 
 def format_exception(t=None, e=None, tb=None):
@@ -44,7 +44,7 @@ def format_exception(t=None, e=None, tb=None):
             # Assert data saneness
             if data['type'] not in ['execute', 'evaluate']:
                 raise Exception('Python bridge call `type` must be `execute` or `evaluate`')
-            if not isinstance(data['code'], six.string_types):
+            if not isinstance(data['code'], UNICODE_TYPE):
                 raise Exception('Python bridge call `code` must be a string.')
 
             # Run Python code