Add get_item_vector accessor

Change-Id: I52c7333fe0f3d9d3eef4e424747a1719ab5ba4c0
Reviewed-on: https://gerrit.spotify.net/gerrit/79702
TC-Compile-And-Test: Team City <teamcity@spotify.com>
Reviewed-by: Erik Bernhardsson <erikbern@spotify.com>
moved python interface to its own class

Change-Id: I9a4b216d77ca5601edaff4a45c61252d7b65fcc5
Reviewed-on: https://gerrit.spotify.net/gerrit/83592
TC-Compile-And-Test: Team City <teamcity@spotify.com>
Reviewed-by: Andy Sloane <as@spotify.com>
Reviewed-by: Erik Bernhardsson <erikbern@spotify.com>