tests/testem/2var_data.tab

   1 sample_id       0       1
   2 sample_0        0       1
   3 sample_1        0       1
   4 sample_2        0       1
   5 sample_3        0       1
   6 sample_4        0       1
   7 sample_5        0       1
   8 sample_6        0       1
   9 sample_7        0       1
  10 sample_8        0       1
  11 sample_9        0       0
  12 sample.0        1       1
  13 sample.1        1       1
  14 sample.2        1       1
  15 sample.3        1       0
  16 sample.4        1       0
  17 sample.5        1       0
  18 sample.6        1       0
  19 sample.7        1       0
  20 sample.8        1       0
  21 sample.9        1       0