English
testBit distributes over bitwise OR: testBit (m ||| n) k = (testBit m k) ∨ (testBit n k).
Русский
testBit распределяется через побитовое OR: testBit (m ||| n) k = testBit m k ∨ testBit n k.
LaTeX
$$$$ \\text{testBit}(m\\,|||\\,n)\\,k = \\text{testBit}(m)\\,k \\lor \\text{testBit}(n)\\,k $$$$
Lean4
theorem testBit_lor : ∀ m n k, testBit (m ||| n) k = (testBit m k || testBit n k) :=
testBit_bitwise rfl