Function lemma_u32_clearbit_bit_unchanged 

pub broadcast proof fn lemma_u32_clearbit_bit_unchanged(word: u32, b: int, b2: int)

requires

0 <= b < 32,

0 <= b2 < 32,

b != b2,

ensures

u32_bit_is_set(word & (!(1u32 << (b as usize))), b2) == u32_bit_is_set(word, b2),

Clearing bit b leaves a different in-range bit b2 unchanged.