SimpleProcessor 

If it is not necessary to further process the data transferred by TypoScript, a SimpleProcessor is available. This passes the transferred data directly to the Renderer without any further interaction.

Usage 

tt_content.tx_myextension_mymodule = USER
tt_content.tx_myextension_mymodule {
    userFunc = CPSIT\Typo3Handlebars\DataProcessing\SimpleProcessor->process
    userFunc.templatePath = Extensions/FluidStyledContent/MyModule
}
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As you can see, the SimpleProcessor is directly addressed as userFunc. It already provides the necessary functionality, but can of course also be extended with your own requirements.

Furthermore it is necessary to indicate a template path with (this normally happens in the Presenter). The SimpleProcessor throws an exception, if the template path is not set or invalid.

Sources