Function read_header_ranged 

pub fn read_header_ranged(
    src: &mut dyn RangeSource,
    format: FileFormat,
    stop: &dyn Fn() -> bool,
) -> Result<Header, RangeError>

Read one model header from src with ranged requests: SafeTensors as its first FIRST_SAFETENSORS_RANGE and, when its JSON runs past that, the rest of the JSON and no further; GGUF forward in growing ranges until its tensor infos end. Every bound the file readers keep is kept. stop is asked before each request.