Function write_stack 

pub fn write_stack<W: Write>(
    writer: &mut W,
    stack: &[Felt],
    n: Option<usize>,
    label: &str,
    clk: impl Display,
) -> Result

Writes a stack-like list of elements (operand or advice stack) in the VM’s debug format.

stack is ordered top-first. n is the number of items to show; None shows all of them. label is the human-readable name of the stack (e.g. "Stack" or "Advice stack"), and clk is the clock cycle reported in the header.