Problem: duplicate lines

Code: duplicate+lines/tails_1641823452

Nibbles version: 0.2 | 0.21 | 0.22 | 0.23 | 0.24 | 0.25 | 1.00

Format: Compact | Simple | +Type | Table | JSON | .nbl (DeBruijn) | .nbl (names)

(implicit string concatenation) 
    (implicit string concatenation) 
        @ (= fstLine) 
        "\n" (string) 
    @ (= fstLine)