+-----------------------------------------------+
               |        build-essential:amd64 (= 12.8)         |
               +-----------------------------------------------+
                 |
                 |
                 v
               +----------------------------------------------------+
  +----------> |                                                    |
  |            |                                                    |
  |            |                                                    |
  |    +-----> |               src:gcc-9 (= 9.2.1-21)               |
  |    |       |                                                    |
  |    |       |                                                    |
  |    |    +> |                                                    | <+
  |    |    |  +----------------------------------------------------+  |
  |    |    |    '                                                ^    |
  |    |    |    '                                                |    |
  |    |    |    v                                                |    |
  |    |    |  +-----------------------------------------------+  |    |
  |    |    |  |  texlive-latex-base:all (= 2019.20191208-1)   | -+    |
  |    |    |  +-----------------------------------------------+       |
  |    |    |    |                                                     |
  |    |    |    |                                                     |
  |    |    |    v                                                     |
  |    |    |  +-----------------------------------------------+       |
  |    |    |  |          src:graphite2 (= 1.3.13-11)          |       |
  |    |    |  +-----------------------------------------------+       |
  |    |    |    '                                                     |
  |    |    |    '                                                     |
  |    |    |    v                                                     |
  |    |    |  +-----------------------------------------------+       |
  |    |    +- |       python3-fonttools:all (= 4.0.2-1)       |       |
  |    |       +-----------------------------------------------+       |
  |    |         |                                                     |
  |    +----+    |                                                     |
  |         |    v                                                     |
  |         |  +-----------------------------------------------+       |
  |         |  |           src:numpy (= 1:1.17.4-3)            | <+    |
  |         |  +-----------------------------------------------+  |    |
  |         |    '                                                |    |
  |         |    '                                                |    |
  |         |    v                                                |    |
  |         |  +-----------------------------------------------+  |    |
  |         +- |    python3-matplotlib:amd64 (= 3.0.2-2+b2)    | -+    |
  |            +-----------------------------------------------+       |
  |              |                                                     |
  |              |                                                     |
  |              v                                                     |
  |            +-----------------------------------------------+       |
  |            |          src:matplotlib (= 3.0.2-2)           |       |
  |            +-----------------------------------------------+       |
  |              '                                                     |
  |              '                                                     |
  |              v                                                     |
  |            +-----------------------------------------------+       |
  |            | python3-tornado:amd64 (= 6.0.3+really5.1.1-2) | ------+
  |            +-----------------------------------------------+
  |              |
  |              |
  |              v
  |            +-----------------------------------------------+
  |            |  src:python-tornado (= 6.0.3+really5.1.1-2)   |
  |            +-----------------------------------------------+
  |              '
  |              '
  |              v
  |            +-----------------------------------------------+
  +----------- |       python3-twisted:all (= 18.9.0-5)        |
               +-----------------------------------------------+
                 |
                 |
                 v
               +-----------------------------------------------+
               |        src:zope.interface (= 4.6.0-1)         |
               +-----------------------------------------------+