Validation on editable grid

a!localVariables(
  local!data: {
    a!map(key:1, value:"A"),
    a!map(key:2, value:"B"),
    a!map(key:3, value:"A"),
  },
  a!gridLayout(
    headerCells: {
      a!gridLayoutHeaderCell(label: "Header Cell")
    },
    rows: a!forEach(
      items: local!data,
      expression: a!gridRowLayout(
        id: fv!index,
        contents: {
          a!textField(
            value: fv!item.value,
            saveInto: fv!item.value,
            validations: if(
              contains(
                remove(local!data.value, fv!index),
                fv!item.value
              ),
              "Duplicate",
              null
            )
          )
        }
      )
    ),
  )
)