read_csv(
  "data/ex_2.csv",
  col_types = cols(.default = col_character())
) </td>
  </tr>
  <tr>
   <td style="text-align:left;"> controlling-column-types-11 </td>
   <td style="text-align:left;"> exercise </td>
   <td style="text-align:left;"> read_csv(
  "data/ex_2.csv",
  col_types = cols(.default = col_character())
) %&gt;%
  mutate(a = parse_integer(a)) </td>
  </tr>
  <tr>
   <td style="text-align:left;"> controlling-column-types-12 </td>
   <td style="text-align:left;"> exercise </t