The base class basestring doesn't exist in Python 3. Use string_types from six instead. Change-Id: I7e84903fb7dd4a0af7ae4e9f4ec2e54338f212bb Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-on: https://gem5-review.googlesource.com/c/15998 Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com> Reviewed-by: Juha Jäykkä <juha.jaykka@arm.com>