ImportError: No module named topology_parser

[gz]

root@xxx:~/Simulator# apt-get install python-networkx python-pygraphviz libgv-python python-numpy python-pygraph python-matplotlib
root@xxx:~/Simulator# while [[ 1 ]]; do ./simulator.py --server; sleep 2; done
Traceback (most recent call last):
  File "./simulator.py", line 20, in <module>
    import simulation
  File "/root/Simulator/simulation.py", line 12, in <module>
    import hybrid
  File "/root/Simulator/hybrid.py", line 12, in <module>
    import simplemachine
  File "/root/Simulator/simplemachine.py", line 9, in <module>
    import model
  File "/root/Simulator/model.py", line 14, in <module>
    import topology_parser
ImportError: No module named topology_parser
^C