* New docs [Separate OpenAPI Schemas for Input and Output or Not](https://fastapi.tiangolo.com/how-to/separate-openapi-schemas/).
    * This PR also includes a new setup (internal tools) for generating screenshots for the docs.

### Refactors

(or the parameter lists if the block is the function body) with the same type,
and at least one of the non-<a href="#Blank_identifier">blank</a> variables is new.
As a consequence, redeclaration can only appear in a multi-variable short declaration.
Redeclaration does not introduce a new variable; it just assigns a new value to the original.
The non-blank variable names on the left side of <code>:=</code>
must be <a href="#Uniqueness_of_identifiers">unique</a>.