Function from_fn 

pub fn from_fn<F>(f: F) -> RenderFn
where
    F: FnMut(&Value) -> Result<String, RenderError> + 'static,

Creates a render function from a closure.

This is the primary way to provide custom rendering logic. The closure should capture any context it needs (format, theme, templates, etc.).

Accepts FnMut closures, allowing mutable state in the render handler.

Example

use standout_dispatch::{from_fn, RenderError};

let render = from_fn(|data| {
    Ok(serde_json::to_string_pretty(data)?)
});