fn print(&mut self, expression: Spanned<SST>) -> Result<(), Syntax> {
        self.walk(&expression)?;
        self.lambda.emit(Opcode::Print);
        Ok(())
    }
Generates a print expression
Note that currently printing is a baked-in language feature,
but the second the FFI becomes a thing
it'll no longer be one.
passerine/src/compiler/compile.rs