How can define this type with arktype?

I'm relatively new to runtime validation and I'm having some trouble with arktype's syntax.

This is the valibot's example that I want to replicate:


 metadata: v.optional(
    v.array(
      v.object({
        key: v.string(),
        value: v.string()
      })
    ),
    []
  )


 metadata: v.optional(
    v.array(
      v.object({
        key: v.string(),
        value: v.string()
      })
    ),
    []
  )


 metadata: v.optional(
    v.array(
      v.object({
        key: v.string(),
        value: v.string()
      })
    ),
    []
  )


 metadata: v.optional(
    v.array(
      v.object({
        key: v.string(),
        value: v.string()
      })
    ),
    []
  )

I can't find a similar example on arktype's docs