Objective of issue: Cells output in tutorial 07 are empty

Lava version:

• 0.3.0 (current version)

I'm submitting a ...

• bug report

Current behavior:

• Cells output in tutorial 07 are empty

Expected behavior:

• As described in the tutorial:

The expected output will be the initial value 5 of var at the beginning, followed by 6 (5+1), 8 (6+2), 11 (8+3), 15 (11+4).

The output originally present in the notebook is indeed

Value of var: [5] at time step: 1
Value of var: [6] at time step: 2
Value of var: [8] at time step: 3
Value of var: [11] at time step: 4
Value of var: [15] at time step: 5

But when I run the cells, the output is empty.

Steps to reproduce:

• Run cells in tutorial 07.

Other information
I'm able to run the other tutorials correctly (except 06 which hangs as described in #242)