-- Print-loop: `@x xs{prnt x}` at the function tail no longer double-prints.
-- Previously the loop's last-body-value (the last printed item) was auto-
-- printed again at top level, forcing a trailing `+0 0` sentinel idiom.
-- Now: when the entry function's body ends with a loop AND has no early-
-- return path, the top-level auto-print is suppressed. Loop-as-expression
-- value inside functions is unchanged (callers still see the loop's last
-- body value). Explicit `nil` returns from non-loop tails still print as
-- "nil" — suppression is syntactic loop-tail only, not blanket Nil.
-- `tests/regression_loop_print.rs` covers nested-caller, brk/while, and
-- explicit-nil cases. The annotations below pin the single-line scenarios
-- so `tests/examples_engines.rs` exercises them too.
-- Single-item print-loop at top level: prints "42" once. Pre-fix this
-- printed "42\n42\n".
print-one>n;xs=[42];@x xs{prnt x}
-- Empty-list loop: function returns nil, suppressed at top level
-- (no "nil" line). Stdout is empty.
empty-loop>n;xs=[];@x xs{prnt x}
-- Trailing-expression sentinel: when the syntactic tail is an expression
-- (not a loop), suppression does NOT apply — the value still auto-prints.
-- Stdout: "99".
with-sentinel>n;xs=[];@x xs{prnt x};+99 0
-- run: print-one
-- out: 42
-- run: empty-loop
-- out:
-- run: with-sentinel
-- out: 99