cross.md
In forcats: Tools for Working with Categorical Variables (Factors)

validates its inputs

Code
  fct_cross(x = "x")
Condition
  Error in `fct_cross()`:
  ! Arguments in `...` must be passed by position, not name.
  x Problematic argument:
  * x = "x"
Code
  fct_cross("x", sep = 1)
Condition
  Error in `fct_cross()`:
  ! `sep` must be a single string, not the number 1.
Code
  fct_cross("x", keep_empty = 1)
Condition
  Error in `fct_cross()`:
  ! `keep_empty` must be `TRUE` or `FALSE`, not the number 1.