Adding csv test file

csv_out_test.csv

+x[0],x[1],x[2],column_0,column_1,column_2,column_3,column_4_[0],column_4_[1],column_4_[2],column_5_[0][0],column_5_[0][1],column_5_[0][2],column_5_[1][0],column_5_[1][1],column_5_[1][2],column_5_[2][0],column_5_[2][1],column_5_[2][2]
+1,2,3,1,2,3,4,1,2,7,10,13,8,19,23,5,4,3,11
+1,2,3,1,2,3,4,2,3,8,11,14,9,20,24,6,5,4,12
+1,2,3,1,2,3,4,3,4,9,12,15,10,21,25,7,6,5,13
+1,2,3,1,2,3,4,4,5,10,13,16,11,22,26,8,7,6,14
+1,2,3,1,2,3,4,5,6,11,14,17,12,23,27,9,8,7,15
+1,2,3,1,2,3,4,6,7,12,15,18,13,24,28,10,9,8,16
+1,2,3,1,2,3,4,7,8,13,16,19,14,25,29,11,10,9,17
+1,2,3,1,2,3,4,8,9,14,17,20,15,26,30,12,11,10,18
+1,2,3,0,0,0,0,9,10,15,18,21,16,27,31,13,12,11,19
+1,2,3,0,0,0,0,10,11,16,19,22,17,28,32,14,13,12,20
+1,2,3,0,0,0,0,11,12,17,20,23,18,29,33,15,14,13,21
+1,2,3,0,0,0,0,12,13,18,21,24,19,30,34,16,15,14,22
+1,2,3,0,0,0,0,13,14,19,22,25,20,31,35,17,16,15,23
+1,2,3,0,0,0,0,14,15,20,23,26,21,32,36,18,17,16,24
+1,2,3,0,0,0,0,15,16,21,24,27,22,33,37,19,18,17,25
+1,2,3,0,0,0,0,16,17,22,25,28,23,34,38,20,19,18,26