user
Task

Find positive decimal integers   **n**   in which the digit   **1**   occurs exactly twice,   where   **n   <   1,000**.
assistant
```
say display 10, '%3d', ^1000 .grep: { .comb.Bag{'1'} == 2 };

sub display {
    cache $^c;
    "{+$c} matching:\n" ~ $c.batch($^a)».fmt($^b).join: "\n"
}

```

Yields:

```
27 matching:
 11 101 110 112 113 114 115 116 117 118
119 121 131 141 151 161 171 181 191 211
311 411 511 611 711 811 911
```