Function to_extend 

pub fn to_extend<T, W>(value: &T, writer: W) -> Result<W>
where
    T: Serialize + ?Sized,
    W: Extend<u8>,

Serialize a T to a [core::iter::Extend],

Example

use postcard::to_extend;
let mut vec = Vec::new();

let ser = to_extend(&true, vec).unwrap();
let vec = to_extend("Hi!", ser).unwrap();
assert_eq!(&vec[0..5], &[0x01, 0x03, b'H', b'i', b'!']);