#Class definition for a vertex in a tree

class Vertex():

    #Initializes a vertex with no children labelled "data"
    def __init__(self, data=""):
        self.data = data
        self.children = []

    #Method for adding vertices to the tree as children of a specific vertex
    #Note, duplicates will be added
    def add(self, parent, child2):
        if self.data == parent:
            self.children.append(Vertex(child2))
        else:
            for child in self.children:
                child.add(parent, child2)

    #Prints the content of a tree with indendation to show ancestry
    def printTree(self, s = "---"):
        print(s + self.data)
        s = "   " + s
        for child in self.children:
            child.printTree(s)

    #Returns the preorder traversal of a tree as an array of Vertex objects
    def preorder(self, s = []):
        s.append(self.data)
        for child in self.children:
            child.preorder(s)
        return s

    #Returns the inorder traversal of a tree as an array of Vertex objects
    def inorder(self, s = []):
        if len(self.children) > 0:
            self.children[0].inorder(s)
        s.append(self.data)
        if len(self.children) > 1:
            for child in self.children[1:]:
                child.inorder(s)
        return s

t = Vertex('a')

t.add('a','b')
t.add('a','c')
t.add('c','d')
t.add('c','e')
t.add('b','f')

t.printTree()

t.preorder()

t.inorder()