human
Solve the following python programming problem given the following code:
# %load test_bst_validate.py
from nose.tools import assert_equal

class TestBstValidate(object):

    def test_bst_validate(self):
        node = Node(5)
        insert(node, 8)
        insert(node, 5)
        insert(node, 6)
        insert(node, 4)
        insert(node, 7)
        assert_equal(validate_bst(node), True)

        root = Node(5)
        left = Node(5)
        right = Node(8)
        invalid = Node(20)
        root.left = left
        root.right = right
        root.left.right = invalid
        assert_equal(validate_bst(root), False)
        print('Success: test_bst_validate')

def main():
    test = TestBstValidate()
    test.test_bst_validate()

if __name__ == '__main__':
    main()
Given the above code, generate some markdown instructions for it.
assistant
#Here is the Python program you requested.

Unit Test
The following unit test is expected to fail until you solve the challenge.