YAPF
diff --git a/yapf/yapflib/format_token.py b/yapf/yapflib/format_token.py
index 98417a2..d86c16d 100644
--- a/yapf/yapflib/format_token.py
+++ b/yapf/yapflib/format_token.py
@@ -281,8 +281,7 @@
     else:
       prefix = "[uUbB]?[rR]?"
 
-    regex = r'^{prefix}(?P<delim>"""|\'\'\').*(?P=delim)$'.format(
-        prefix=prefix)
+    regex = r'^{prefix}(?P<delim>"""|\'\'\').*(?P=delim)$'.format(prefix=prefix)
     return (self.is_string and
             re.match(regex, self.value, re.DOTALL) is not None)