variable with tree structure save to txt file python

****this code reads the structure tree from the cad software CATIA. i need to save the tree in a txt file but it doesn't work ... thanks for help.****

already tried:

import pickle
file = open('dump.txt', 'w')
pickle.dump(tree, file)
file.close()




from catialib import *
a=CatiaLibrary()
a.OpenFile("Mastermodell.CATPart")
tree=a.ReadTree(show=False)
print (tree)
a.CloseWindow()