The  dpkg --configure -a  and  apt-get -f install  dance brought me to this point:

$ sudo dpkg --configure -a
dpkg: dependency problems prevent configuration of rhythmbox-plugins:
 rhythmbox-plugins depends on python3 (>= 3.6~); however:
  Version of python3 on system is 3.5.1-3.

dpkg: error processing package rhythmbox-plugins (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of libgoa-backend-1.0-1:amd64:
 libgoa-backend-1.0-1:amd64 depends on libgoa-1.0-0b (>= 3.25.4); however:
  Version of libgoa-1.0-0b:amd64 on system is 3.18.3-1ubuntu2.

dpkg: error processing package libgoa-backend-1.0-1:amd64 (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of python3-apt:
 gnupg (2.2.4-1ubuntu1) breaks python3-apt (<= 1.1.0~beta4) and is installed.
  Version of python3-apt to be configured is 1.1.0~beta1ubuntu0.16.04.1.

dpkg: error processing package python3-apt (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of rhythmbox-plugin-magnatune:
 rhythmbox-plugin-magnatune depends on rhythmbox-plugins; however:
  Package rhythmbox-plugins is not configured yet.

dpkg: error processing package rhythmbox-plugin-magnatune (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of python3-gdbm:amd64:
 python3-gdbm:amd64 depends on python3 (>= 3.6.4-1~); however:
  Version of python3 on system is 3.5.1-3.

dpkg: error processing package python3-gdbm:amd64 (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of python3-reportlab-accel:amd64:
 python3-reportlab-accel:amd64 depends on python3 (>= 3.6~); however:
  Version of python3 on system is 3.5.1-3.

dpkg: error processing package python3-reportlab-accel:amd64 (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of python3-cairo:amd64:
 python3-cairo:amd64 depends on python3 (>= 3.6~); however:
  Version of python3 on system is 3.5.1-3.

dpkg: error processing package python3-cairo:amd64 (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of python-apt:
 python-apt depends on libapt-inst2.0 (>= 1.4~beta3); however:
  Version of libapt-inst2.0:amd64 on system is 1.2.26.
 python-apt depends on libapt-pkg5.0 (>= 1.4~beta3); however:
  Version of libapt-pkg5.0:amd64 on system is 1.2.26.

dpkg: error processing package python-apt (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of onboard:
 onboard depends on python3-cairo; however:
  Package python3-cairo:amd64 is not configured yet.
 onboard depends on python3 (>= 3.6~); however:
  Version of python3 on system is 3.5.1-3.

dpkg: error processing package onboard (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of software-properties-common:
 gnupg (2.2.4-1ubuntu1) breaks software-properties-common (<= 0.96.24.3) and is installed.
  Version of software-properties-common to be configured is 0.96.20.7.

dpkg: error processing package software-properties-common (--configure):
 dependency problems - leaving unconfigured
dpkg: dependency problems prevent configuration of unity-control-center:
 unity-control-center depends on libgoa-backend-1.0-1 (>= 3.18.0); however:
  Package libgoa-backend-1.0-1:amd64 is not configured yet.

dpkg: error processing package unity-control-center (--configure):
 dependency problems - leaving unconfigured
Errors were encountered while processing:
 rhythmbox-plugins
 libgoa-backend-1.0-1:amd64
 python3-apt
 rhythmbox-plugin-magnatune
 python3-gdbm:amd64
 python3-reportlab-accel:amd64
 python3-cairo:amd64
 python-apt
 onboard
 software-properties-common
 unity-control-center


$ sudo apt-get -f install
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Correcting dependencies... failed.
The following packages have unmet dependencies:
 gnome-bluetooth : Depends: libpam-systemd but it is not installed
 gnome-session : Depends: gnome-settings-daemon (>= 3.0) but it is not installed
 gnupg : Breaks: python3-apt (<= 1.1.0~beta4) but 1.1.0~beta1ubuntu0.16.04.1 is installed
         Breaks: software-properties-common (<= 0.96.24.3) but 0.96.20.7 is installed
 libc6-dbg : Depends: libc6 (= 2.23-0ubuntu10) but 2.27-3ubuntu1 is installed
 libgoa-1.0-0b : Depends: libgoa-1.0-common (= 3.18.3-1ubuntu2) but 3.28.0-0ubuntu2 is installed
 libgoa-backend-1.0-1 : Depends: libgoa-1.0-0b (>= 3.25.4) but 3.18.3-1ubuntu2 is installed
 network-manager : Depends: libpam-systemd but it is not installed
 onboard : Depends: python3 (>= 3.6~) but 3.5.1-3 is installed
           Recommends: onboard-data (>= 1.4.1-2ubuntu1) but 1.2.0-0ubuntu5 is installed
 policykit-1 : Depends: libpam-systemd but it is not installed
 pulseaudio : Depends: libpam-systemd but it is not installed
 python-apt : Depends: libapt-inst2.0 (>= 1.4~beta3) but 1.2.26 is installed
              Depends: libapt-pkg5.0 (>= 1.4~beta3) but 1.2.26 is installed
 python3 : PreDepends: python3-minimal (= 3.5.1-3) but 3.6.5-3 is installed
           Depends: libpython3-stdlib (= 3.5.1-3) but 3.6.5-3 is installed
 python3-cairo : Depends: python3 (>= 3.6~) but 3.5.1-3 is installed
 python3-gdbm : Depends: python3 (>= 3.6.4-1~) but 3.5.1-3 is installed
 python3-reportlab-accel : Depends: python3 (>= 3.6~) but 3.5.1-3 is installed
 rhythmbox-plugins : Depends: python3 (>= 3.6~) but 3.5.1-3 is installed
 systemd : Depends: libsystemd0 (= 229-4ubuntu21.2) but 237-3ubuntu10 is installed
           Recommends: libpam-systemd but it is not installed
 udisks2 : Depends: libpam-systemd but it is not installed
 urfkill : Depends: libpam-systemd but it is not installed
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.
E: Unable to correct dependencies