para que serve esse "modules" em ivStartApp.py ?

 modules ={'ivVolumeFile': [0, '', 'ivVolumeFile.py'],
 'ivDicomParser': [0, '', 'ivDicomParser.py'],
 'ivTab_SliceEditor': [0, '', 'ivTab_SliceEditor.py'],
 'ivDataSet': [0, '', 'ivDataSet.py'],
 'ivMainControl': [0, '', 'ivMainControl.py'],
 'ivFrm_Main': [0, '', 'ivFrm_Main.py'],
 'ivTab_Model': [0, '', 'ivTab_Model.py'],
 'ivPanel_Slices2D': [0, '', 'ivPanel_Slices2D.py'],
 'ivProject': [0, '', 'ivProject.py'], 'ivTab_Segmentation': [0, '', 'ivTab_Segmentation.py'],
 'ivTab_Segmentation_Morph': [0,'', 'ivTab_Segmentation_Morph.py'],
 'ivTab_Segmentation_Island': [0,'','ivTab_Segmentation_Island.py'],
 'ivTab_Segmentation_Island_Draw': [0,'','ivTab_Segmentation_Island_Draw.py'],
 'ivTab_Segmentation_Island_LiveWire': [0,'','ivTab_Segmentation_Island_LiveWire.py'],
 'ivTab_Segmentation_Island_BinThresh': [0,'','ivTab_Segmentation_Island_BinThresh.py'],
 'ivTab_Segmentation_RegionGrow': [0,'','ivTab_Segmentation_RegionGrow.py'],
 'ivTab_Segmentation_RegionGrow_Confidence': [0,'','ivTab_Segmentation_RegionGrow_Confidence.py'],
 'ivTab_Segmentation_RegionGrow_Isolate': [0,'','ivTab_Segmentation_RegionGrow_Isolate.py'],
 'ivTab_Segmentation_RegionGrow_Neighbour': [0,'','ivTab_Segmentation_RegionGrow_Neighbour.py'],
 'ivTab_Segmentation_RegionGrow_BinThresh': [0,'','ivTab_Segmentation_RegionGrow_BinThresh.py'],
 'ivTab_Segmentation_Thresh': [0,'','ivTab_Segmentation_Thresh.py'],
 'ivActorsVTK': [0, '', 'ivActorsVTK.py'],
 'ivVars': [0, '', 'ivVars.py'],
 'ivTab_Visualization': [0, '', 'ivTab_Visualization.py'],
 'ivTab_Visualization_Default': [0,'','ivTab_Visualization_Default.py'],
 'ivTab_Visualization_SliceGroup': [0,'','ivTab_Visualization_SliceGroup.py']}

Autor: Thomaz dos Reis