      a     b c     d     e      f          g                  
  <dbl> <int> <lgl> <chr> <fctr> <date>     <dttm>             
1  1.00     1 T     a     a      2015-12-10 2015-12-09 10:51:35
2  2.50     2 F     b     b      2015-12-11 2015-12-09 10:51:36
3 NA       NA NA    <NA>  <NA>   NA         NA                 
  h         i         
  <list>    <list>    
1 <int [1]> <list [2]>
2 <int [1]> <list [1]>
3 <int [1]> <list [1]>
