Simple Tree : Python

I needed a simple example on using list in Python for
a Python tutorial :
This sample shows a way to diplay a hierachical list

tree=["Serveurs",
        ["Dakar",
            ["System",
             "Banque",
             "Reseaux",
                 ['R1',
                  'R2']],
         "Dublin",
         "Denver",
         "Douala",
             ["Queue"]]]

hidedNodes = []


def displayTree(tree,n=0):
    ident = "   "
    nextitem = None
    for item in tree:
        if not isinstance(item,list):
            try:
                nextitem  =  tree[tree.index(item)+1]
            except:
                pass
            if isinstance(nextitem, list):
                print n*ident+"+" + item
                if item in hidedNodes:
                    if nextitem[0] != 'x':
                        nextitem.insert(0,'x')
                else:
                    try:
                        nextitem.remove('x')
                    except:
                        pass
            else:
                print n*ident+" "+ item
        else:
            if not nextitem[0] == 'x':
                n = n + 1
                displayTree(nextitem,n)
                n = n -1


def hideNode(node):
    hidedNodes.append(node)

def showNode(node):
    hidedNodes.remove(node)

def test():
    print "TEST 1 : Display all"
    displayTree(tree)
    print ""
    print "TEST 2 : Hiding Douala,Dakar"
    map(hideNode,['Dakar','Douala'])
    displayTree(tree)
    print ""
    print "TEST 3 : Showing Dakar"
    showNode('Dakar')
    displayTree(tree)
    print ""
    print "TEST 4: Hide Reseaux"
    hideNode('Reseaux')
    displayTree(tree)

if __name__ == "__main__":
    test()