Function exec_stmts 

pub fn exec_stmts(
    stmts: &[(Stmt, bool)],
    env: &mut Env,
    io: &mut IoContext,
    fmt: &FormatMode,
    base: Base,
    compact: bool,
) -> Result<Option<Signal>, String>

Executes a sequence of parsed statements, handling flow control signals.

Returns:

• Ok(None) — normal completion
• Ok(Some(Signal::Break)) — break statement executed
• Ok(Some(Signal::Continue)) — continue statement executed
• Err(e) — runtime error

Loop implementations (For, While) catch Break/Continue internally. A signal that escapes to the top-level caller should be reported as an error.