def path_exists(path):
    return os.path.exists(path)
Returns the hash of the previous block, with the bytes in the order
dataset/ETHPy150Open BU-NU-CLOUD-SP16/Trusted-Platform-Module-nova/nova/virt/libvirt/utils.py/path_exists--crossover with--dataset/ETHPy150Open maraoz/proofofexistence/pycoin/block.py/BlockHeader.previous_block_id