funcs.md: Fix mistakes and add example.

[emosenkis]

No description provided.

[jhnnsrs]

Thanks so much for your efforts! Really much appreciated :) especially the documentation needs so much more love. Do you have any suggestions?

[emosenkis]

Thank you for making this tool! I don't remember any other documentation issues but I did run into some issues with the generated code that I worked around by modifying it after generation completed:

• it crashes when graphqlrc is missing extensions.turms for any project, not just the one I asked it to generate
• it can't continue if any fragment is unused
• default values for global kwargs keep the type they have in the YAML file, making it impossible to use a non-trivial default value (e.g. setting default: utils.Unset results in python some_arg: SomeType = "utils.Unset", resulting in a string instead of the value of the UNSET constant)
• imports needed to provide the default value of a kwarg aren't added automatically
• imports for complex types don't work (e.g. using type: dict[str, Any] results in invalid imports)
• having a scalar definition with python type None results in invalid syntax None | None (TypeError: unsupported operand type(s) for |: 'NoneType' and 'NoneType')

And some feature requests:

• I would like to have an option to generate one file for each input graphql that defines operations, e.g. foo/SomeOperation.graphql -> foo/SomeOperation.py or even better foo/some_operation.generated.py - I'm used to having this from the codegen we use for TypeScript
• ruff support as an alternative to black