outputs the row number where aline has been defined. This can be useful for writing custom text viewers or editors in Logo, like the attemps in formulatest.lg.
fd 100 rt 90
foreach bf makeTreeFromBody text "p1 [(show LineRow ? ?)]
40 [fd 100] ;numbers may vary, depending on where/when p1 was defined
40 [rt 90]
41 [fd 50]
42 [rt 45]