AttributeError: Unable to retrieve attribute 'x'

[jvence]

Cannot run demo as I keep getting: AttributeError: Unable to retrieve attribute 'x' in:

Cell In[48], [line 6](vscode-notebook-cell:?execution_count=48&line=6) [4](vscode-notebook-cell:?execution_count=48&line=4) pair = [] [5](vscode-notebook-cell:?execution_count=48&line=5) for i in I: ----> [6](vscode-notebook-cell:?execution_count=48&line=6) if x[i, j].x == 1: [7](vscode-notebook-cell:?execution_count=48&line=7) pair.append(i) [8](vscode-notebook-cell:?execution_count=48&line=8) pair.append(j)

I guess error is due because I don't have a valid Gurobi license.