pub trait ExtensionArrayTrait: Array {
    // Required method
    fn storage_data(&self) -> ArrayRef;
    // Provided method
    fn ext_dtype(&self) -> &Arc<ExtDType> { ... }
}pub trait ExtensionArrayTrait: Array {
    // Required method
    fn storage_data(&self) -> ArrayRef;
    // Provided method
    fn ext_dtype(&self) -> &Arc<ExtDType> { ... }
}