diff --git a/prexview.py b/prexview.py
index 9ff5f61..3a6bdfd 100644
--- a/prexview.py
+++ b/prexview.py
@@ -28,8 +28,8 @@ def __send(self, data):
 
     response = post(self._URL + 'transform', data = data, headers = headers)
 
-    if response.raise_for_status() is not None:
-      return None
+    if response.status_code != 200:
+      raise Exception(loads(response.content)['error'])
 
     result = {
       'rateLimit': response.headers['x-ratelimit-limit'],
@@ -37,7 +37,7 @@ def __send(self, data):
       'rateRemaining': response.headers['x-ratelimit-remaining'],
     }
 
-    if response.status_code is 200:
+    if response.status_code == 200:
       result['id'] = response.headers['x-transaction-id']
       result['file'] = response.content
       result['responseTime'] = response.headers['x-response-time']
@@ -47,14 +47,14 @@ def __send(self, data):
   def __isJson(self, str):
     try:
       json = loads(str)
-    except ValueError, e:
+    except ValueError as e:
       return False
 
     return True
 
   def __checkOptions(self, _format, options):
     # JSON
-    if _format is 'json':
+    if _format == 'json':
       if type(options['json']) is str:
         if self.__isJson(options['json']) is not True:
           raise Exception('PrexView content must be a valid JSON string')
@@ -104,7 +104,7 @@ def __checkOptions(self, _format, options):
     return options
 
   def __checkToken(self):
-    if self.token is None or self.token is '':
+    if self.token is None or self.token == '':
       raise Exception('PrexView environment variable PXV_API_KEY must be set')
 
   def sendXML(self, content, options):
diff --git a/tests/test_json.py b/tests/test_json.py
index bf25459..5e9c2ac 100644
--- a/tests/test_json.py
+++ b/tests/test_json.py
@@ -1,7 +1,7 @@
 # coding: utf-8
-from prexview import Prexview
+from prexview import PrexView
 
-pxv = Prexview()
+pxv = PrexView()
 options = {'design': 'custom-invoice', 'output': 'pdf'}
 
 json = {
@@ -21,6 +21,6 @@
     f.write(res['file'])
     f.close()
 
-  print 'File created:', file
+  print('File created:', file)
 except Exception as e:
-  print e
+  print(e)
diff --git a/tests/test_xml.py b/tests/test_xml.py
index d3e000e..096f87c 100644
--- a/tests/test_xml.py
+++ b/tests/test_xml.py
@@ -1,7 +1,7 @@
 # coding: utf-8
-from prexview import Prexview
+from prexview import PrexView
 
-pxv = Prexview()
+pxv = PrexView()
 options = dict(design='custom-invoice', output='pdf')
 
 xml = '''<?xml version="1.0" encoding="UTF-8"?>
@@ -20,6 +20,6 @@
     f.write(res['file'])
     f.close()
 
-  print 'File created:', file
+  print('File created:', file)
 except Exception as e:
-  print e
+  print(e)