pub(crate) fn arg_info_flags(pass_by_ref: bool, is_variadic: bool) -> u32 {
        (u32::from(pass_by_ref) << _ZEND_SEND_MODE_SHIFT)
            | (if is_variadic {
                _ZEND_IS_VARIADIC_BIT
            } else {
                0
            })
    }
Calculates the internal flags of the type.
Translation of of the `_ZEND_ARG_INFO_FLAGS` macro from
`zend_API.h:110`.

# Parameters

* `pass_by_ref` - Whether the value should be passed by reference.
* `is_variadic` - Whether this type represents a variadic argument.
src/zend/_type.rs