Today I learned that collections.deque is implemented as a doubly-linked list of blocks.
collections.deque
Today I learned Python 3.15 will get a new sentinel built-in.
⎕←⎕ucs 2∘⊥∘⌽¨ ↓7 (⊢⍴⍨⊣,⍨÷⍨∘≢) ⍎¨ '0001011001011100101110000111110', '0111010111011110101111010101101', '1100001100101110001011110011100', '0011100001110111010110001111110111011011'