Implement left(n), right(n), preorder(T, n), postorder(T, n), and eulertour(T, n) within the following python code:

def left(n): # return the index of the left child of the node at index n

def right(n): # return the index of the right child of the node at index n

def preorder(T, n): # node, left, right def postorder(T, n): # left, right, node

def inorder(T, n): # left, node, right if n < len(T) and T[n] != None: inorder(T, left(n)) print(T[n], end=" ") inorder(T, right(n)) return True return False

def eulertour(T, n): # node, left, (node if left was visited,) right, (node if right was visited)

if __name__ == "__main__": T = ['+', '*', '*', '2', '-', '3', '2', None, None, '5', '1'] print("preorder:") preorder(T, 0) print(" postorder:") postorder(T, 0) print(" inorder:") inorder(T, 0) print(" euler tour:") eulertour(T, 0)

''' Expected output:

preorder: + * 2 - 5 1 * 3 2 postorder: 2 5 1 - * 3 2 * + inorder: 2 * 5 - 1 + 3 * 2 euler tour: + * 2 * - 5 - 1 - * + * 3 * 2 * + '''