Use with block to open file

driver.py

@@ -40,9 +40,8 @@ tests_path = 'test/'
 
 def readfile(fname):
     '''Reads a file as string and returns its content'''
-    fd = open(fname, encoding='utf-8')
+    with open(fname, encoding='utf-8') as fd:
         expr = fd.read()
-    fd.close()
         return expr