Function create_first 

pub fn create_first(
    req: &Request,
    i: usize,
    symbol: &str,
    allocated: usize,
) -> Option<String>

target_missing { symbol } for a $new.n no earlier effect created (plain requests): the next create moved before the effect that uses it, the symbol renamed to the one that create will allocate — $new.<count>, count the symbols allocated so far.