Macro sym 

macro_rules! sym {
    ($raw:literal) => { ... };
    (&$canonical:expr) => { ... };
}

Short syntax for constructing a SymbolInput.

• sym!("BTCUSDT") → SymbolInput::Raw("BTCUSDT")
• sym!(&my_symbol) → SymbolInput::Canonical(&my_symbol)

For canonical from base/quote literals, construct Symbol directly: Symbol::new("BTC", "USDT") then pass via sym!(&sym) or (&sym).into().