Function pick_variant 

pub fn pick_variant(theme: &NativeTheme, is_dark: bool) -> Option<&ThemeVariant>

👎Deprecated since 0.3.2:

Use NativeTheme::pick_variant() instead

Select light or dark variant from a native_theme::NativeTheme, with cross-fallback.

When is_dark is true, prefers theme.dark and falls back to theme.light. When is_dark is false, prefers theme.light and falls back to theme.dark.

Returns None only if the theme has no variants at all.