unite.md
In tidyr: Tidy Messy Data

validates its inputs

Code
  unite(df)
Condition
  Error in `unite()`:
  ! `col` is absent but must be supplied.
Code
  unite(df, "z", x:y, sep = 1)
Condition
  Error in `unite()`:
  ! `sep` must be a single string, not the number 1.
Code
  unite(df, "z", x:y, remove = 1)
Condition
  Error in `unite()`:
  ! `remove` must be `TRUE` or `FALSE`, not the number 1.
Code
  unite(df, "z", x:y, na.rm = 1)
Condition
  Error in `unite()`:
  ! `na.rm` must be `TRUE` or `FALSE`, not the number 1.