@Marvin tell me what prefect blocks are? using prefect 3

In Prefect 3, blocks serve as a way to manage configuration, storage, infrastructure, and secrets for deployments or flow scripts. Essentially, blocks are Python classes designed to interact with external systems and provide specific methods for tasks like downloading or uploading data to an S3 bucket, querying or writing data to a database, or sending messages to a Slack channel. Prefect blocks have a dual interface: they can be manipulated via Python code or through a UI web form. This makes them flexible and accessible, allowing for sharing and storing of configurations across different flow runs and between various workflows in your Prefect Cloud account or self-hosted Prefect server. Example usages of Prefect blocks include: 1. Configuration Sharing: Manage common configurations that multiple flow runs might need. If certain configurations change between runs, using parameters separate from blocks is recommended. 2. Built-in Blocks: Prefect includes several built-in block types that are ready to use without additional installation. These can be accessed and configured via the UI. Blocks are extremely versatile, allowing customization by subclassing the

Block

class, which builds on Pydantic’s

BaseModel

. You can declare custom blocks similarly to how you define a Pydantic model, including the ability to add custom methods to provide additional functionalities. For more details, you can explore the documentation here. This should provide a good snapshot of what blocks are in Prefect and how you can use them to enhance your workflows. If you want to explore more use cases or details, feel free to check Prefect's official docs or tutorials.