tibble [3 × 9] (S3: tbl_df/tbl/data.frame)
 $ a: num [1:3] 1 2.5 NA
 $ b: int [1:3] 1 2 NA
 $ c: logi [1:3] TRUE FALSE NA
 $ d: chr [1:3] "a" "b" NA
 $ e: Factor w/ 2 levels "a","b": 1 2 NA
 $ f: Date[1:3], format: "2015-12-10" "2015-12-11" ...
 $ g: POSIXct[1:3], format: "2015-12-09 10:51:35" "2015-12-09 10:51:36" ...
 $ h:List of 3
  ..$ : int 1
  ..$ : int 2
  ..$ : int NA
 $ i:List of 3
  ..$ :List of 2
  .. ..$ : num 1
  .. ..$ : int [1:2] 2 3
  ..$ :List of 1
  .. ..$ : int [1:3] 4 5 6
  ..$ :List of 1
  .. ..$ : logi NA
