Dont allow unsued globals and allow fp (google#12190)

.pylintrc

@@ -247,6 +247,7 @@ function-naming-style=snake_case
 good-names=i,
            j,
            k,
+           fp,
            ex,
            Run,
            _
@@ -438,7 +439,7 @@ spelling-store-unknown-words=no
 additional-builtins=
 
 # Tells whether unused global variables should be treated as a violation.
-allow-global-unused-variables=yes
+allow-global-unused-variables=no
 
 # List of strings which can identify a callback function by name. A callback
 # name must start or end with one of those strings.