check bst py

arbore_binar_cautare = { "value" : 4, "left":
                             {"value": 2, "left": {"value": 1, "left": None, "right": None}, "right": {"value": 3, "left": None, "right": None},
                             }, "right":
                             {"value": 7, "left": None, "right": None}
                          }

def isBinSrcTree(tree):
    def utilIsBinSrcTree(tree):
        ok = True
        if tree['left'] is not None:
            ok &= tree['value'] > utilIsBinSrcTree(tree['left'])[1]
        if tree['right'] is not None:
            ok &= tree['value'] < utilIsBinSrcTree(tree['right'])[1]
        return ok, tree['value']

    return utilIsBinSrcTree(tree)[0]

print(isBinSrcTree(arbore_binar_cautare))