Function holds_accumulator 

pub fn holds_accumulator(
    op: &Op,
    g: &TensorGraph,
    bits: u32,
) -> Result<(), String>

Whether a chip whose integers accumulate in bits holds every partial result op accumulates: Ok, or why not — the bits its operands’ proven ranges need, or an operand no range bounds on a chip narrower than the language’s own 64-bit integers.