Fix python linter issues

Author: Dave Abrahams

utils/gyb.py

@@ -1237,8 +1237,8 @@ def succ(a):
              Line directive format string, which will be
              provided 2 substitutions, `%%(line)d` and `%%(file)s`.
 
-             Example: `// ###sourceLocation(file: "%%(file)s", line: %%(line)d)`
-             
+             Example: `#sourceLocation(file: "%%(file)s", line: %%(line)d)`
+
              The default works automatically with the `line-directive` tool, 
              which see for more information.
              ''')