satoshi's blockchain is append only data structure ...
script
"“I can’t go back, can I?” a dejected Neo asked.
“No, but if you could, would you really want to? The mind has trouble letting go.”
Seeing the hopelessness and despair in Neo, Morpheus continued, “When the Matrix [world] was first"
https://www.youtube.com/watch?v=HZnKJaEbZjo