Default trait for variables

[danielboros1990]

Hi guys,

is it possible to use Default trait instead of writing None for nullable values.

// current solutions
set: StreamsSetInput {
                        id: None,
                        user_id: None,
                        stream_id: None,
                        is_online: None,
                        live_ms: Some(stream.live_ms.unwrap().to_string()),
                        frames: Some(stream.frames.unwrap().to_string()),
                        send_bytes: Some(stream.send_bytes.unwrap().to_string()),
                        recv_bytes: Some(stream.recv_bytes.unwrap().to_string()),
                        video_codec: Some(stream.video.as_ref().unwrap().codec.clone().unwrap()),
                        video_profile: Some(
                            stream.video.as_ref().unwrap().profile.clone().unwrap(),
                        ),
                        video_level: Some(stream.video.as_ref().unwrap().level.clone().unwrap()),
                        video_width: Some(stream.video.as_ref().unwrap().width.unwrap().into()),
                        video_height: Some(stream.video.as_ref().unwrap().height.unwrap().into()),
                        audio_codec: Some(stream.audio.as_ref().unwrap().codec.clone()),
                        audio_sample_rate: Some(stream.audio.as_ref().unwrap().sample_rate.into()),
                        audio_channel: Some(stream.audio.as_ref().unwrap().channel.into()),
                        audio_profile: Some(stream.audio.as_ref().unwrap().profile.clone()),
                        created_at: None,
                        updated_at: None,
                    },

// expected solutions
set: StreamsSetInput {
                        live_ms: Some(stream.live_ms.unwrap().to_string()),
                        frames: Some(stream.frames.unwrap().to_string()),
                        send_bytes: Some(stream.send_bytes.unwrap().to_string()),
                        recv_bytes: Some(stream.recv_bytes.unwrap().to_string()),
                        video_codec: Some(stream.video.as_ref().unwrap().codec.clone().unwrap()),
                        video_profile: Some(
                            stream.video.as_ref().unwrap().profile.clone().unwrap(),
                        ),
                        video_level: Some(stream.video.as_ref().unwrap().level.clone().unwrap()),
                        video_width: Some(stream.video.as_ref().unwrap().width.unwrap().into()),
                        video_height: Some(stream.video.as_ref().unwrap().height.unwrap().into()),
                        audio_codec: Some(stream.audio.as_ref().unwrap().codec.clone()),
                        audio_sample_rate: Some(stream.audio.as_ref().unwrap().sample_rate.into()),
                        audio_channel: Some(stream.audio.as_ref().unwrap().channel.into()),
                        audio_profile: Some(stream.audio.as_ref().unwrap().profile.clone()),
                        ..Default::default()
                    },