Do not use mutable objects as default arguments.

REF: http://docs.python-guide.org/en/latest/writing/gotchas/

bigcommerce/connection.py

@@ -44,7 +44,12 @@ def __init__(self, host, auth, api_path='/api/v2/{}'):
     def full_path(self, url):
         return "https://" + self.host + self.api_path.format(url)
 
-    def _run_method(self, method, url, data=None, query={}, headers={}):
+    def _run_method(self, method, url, data=None, query=None, headers=None):
+        if query is None:
+            query = {}
+        if headers is None:
+            headers = {}
+
         # make full path if not given
         if url and url[:4] != "http":
             if url[0] == '/':  # can call with /resource if you want
@@ -118,7 +123,7 @@ def delete(self, resource, rid=None):  # note that rid can't be 0 - problem?
 
     # Raw-er stuff
 
-    def make_request(self, method, url, data=None, params = {}, headers = {}):
+    def make_request(self, method, url, data=None, params=None, headers=None):
         response = self._run_method(method, url, data, params, headers)
         return self._handle_response(url, response)
 
@@ -249,4 +254,4 @@ def _handle_response(self, url, res, suppress_empty=True):
                                    window_size_ms=res.headers['X-Rate-Limit-Time-Window-Ms'],
                                    requests_remaining=res.headers['X-Rate-Limit-Requests-Left'],
                                    requests_quota=res.headers['X-Rate-Limit-Requests-Quota'])
-        return result
+        return result