Oops.  Return -1 to distinguish error from empty dict.
Oops.  Return -1 to distinguish error from empty dict.

This change probably isn't work a bug fix.  It's unlikely that anyone
was calling this method without passing it a real dict.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator