pub struct Formatter<'a, 'b: 'a>(_);
A formatter used to serialize headers to an output stream.
Format one 'line' of a header.
This writes the header name plus the
Display value as a single line.
This has the ability to format a header over multiple lines.
The main example here is
Set-Cookie, which requires that every
cookie being set be specified in a separate line. Almost every other
case should only format as 1 single line.