Close index file handle correctly on save/load

influxgraph/classes/tree.py

@@ -109,7 +109,10 @@ def to_file(self, file_h):
         """Dump tree contents to file handle"""
         data = bytes(json.dumps(self.to_array()), 'utf-8') \
           if not isinstance(b'', str) else json.dumps(self.to_array())
-        file_h.write(data)
+        try:
+            file_h.write(data)
+        finally:
+            file_h.close()
 
     def to_array(self):
         """Return array representation of tree index"""
@@ -127,4 +130,6 @@ def from_file(file_h):
         """Load tree index from file handle"""
         data = file_h.read().decode('utf-8') \
           if not isinstance(b'', str) else file_h.read()
-        return NodeTreeIndex.from_array(json.loads(data))
+        index = NodeTreeIndex.from_array(json.loads(data))
+        file_h.close()
+        return index