Function interp_deque_pop_front 

fn interp_deque_pop_front(
    args: &[RValue],
    named: &[(String, RValue)],
    context: &BuiltinContext<'_>,
) -> Result<RValue, RError>

Remove and return the first element of a deque.

Returns NULL if the deque is empty.

@param d integer scalar: deque ID @return the removed value, or NULL if empty