Map() function

What are you not sure about? If you want to know how it is used check the below code.

=a!localVariables(
  local!items: {
    a!map(item: "Item 1", qty: 1, unitPrice: 10),
    a!map(item: "Item 2", qty: 2, unitPrice: 20)
  },
  a!gridLayout(
    label: "Products",
    instructions: "Update the item name, quantity, or unit price.",
    headerCells: {
      a!gridLayoutHeaderCell(label: "Item"),
      a!gridLayoutHeaderCell(label: "Qty"),
      a!gridLayoutHeaderCell(label: "Unit Price"),
      a!gridLayoutHeaderCell(label: "Total", align: "RIGHT")
    },
    rows: {
      a!gridRowLayout(
        contents: {
          a!textField(
            value: local!items[1].item,
            saveInto: local!items[1].item
          ),
          a!integerField(
            value: local!items[1].qty,
            saveInto: local!items[1].qty
          ),
          a!floatingPointField(
            value: local!items[1].unitPrice,
            saveInto: local!items[1].unitPrice
          ),
          a!textField(
            value: dollar(tointeger(local!items[1].qty) * todecimal(local!items[1].unitPrice)),
            readOnly: true,
            align: "RIGHT"
          )
        }
      ),
      a!gridRowLayout(
        contents: {
          a!textField(
            value: local!items[2].item,
            saveInto: local!items[2].item
          ),
          a!integerField(
            value: local!items[2].qty,
            saveInto: local!items[2].qty
          ),
          a!floatingPointField(
            value: local!items[2].unitPrice,
            saveInto: local!items[2].unitPrice
          ),
          a!textField(
            value: dollar(tointeger(local!items[2].qty) * todecimal(local!items[2].unitPrice)),
            readOnly: true,
            align: "RIGHT"
          )
        }
      )
    },
    rowHeader: 1
  )
)