How do I display my BST using my preorder() and inorder() methods?

I'm doing a programming assignment for my class. One of my programs includes creating a BST with Python within a BST class, and I'm trying to display using preorder() and inorder() functions. My professor gave us certain parameters for the assignment, so I've had to code in constraints, but I am struggling with the implementation. I'm not allowed to use self in preorder() and inorder() based on given parameters, nor am I allowed to insert parameters for display(). I want to use the f/function in preorder() and inorder()to call print inside my display() method when calling the functions. X is the value of the root inside the lambda function. However, I know there's a gap in my understanding based on my logic and the problems I'm encountering.

For reference, here is a snippet of my code.

def inorder(f):
   return tree.inorderHelper(root, f)

def inorderHelper(root, f):
    if root:
        tree.inorderHelper(root.left, f)
        f(root.x)
        tree.inorderHelper(root.right, f)  

def preorder(f):
    return tree.preorderHelper(root, f)

def preorderHelper(root, f):
    if root:
        f(root.x)
        tree.preorderHelper(root.left, f)
        tree.preorderHelper(root.right, f)

@staticmethod
def display():
    if random.randint(0,1) == 0:
        tree.preorder(lambda x: print(x, end=" "))
    elif random.randint(0,1) == 1:
        tree.inorder(lambda x: print(x, end=" "))

if __name__ == "__main__":
  print("Hello world!")
  tree = tree()
  root = None
  for i in range(4):
      print(i)
      tree.ins(i)
  tree.display()
  print("Testing preorder")

I've tried creating a printInorder(root) or printPreorder(root) traversal method with similar logic instead of preorder() and inorder() directly, but I always get an error saying that I'm having issues with using too many arguments. I also tried using lambda directly, but I know that's not correct either; I'm getting the same error with arguments. Any help would be appreciated.