fix: update code to match latest MoonBit

[tonyfettes]

No description provided.

[skylee03]

It seems that the panic is caused by the redefinition of Map. Renaming it to MyMap could solve it.

// docs/09
type Map[Key, Value] @immut/list.T[(Key, Value)]
// docs/10
struct Map[K, V] {
  get : (K) -> Option[V]
  put : (K, V) -> Unit
  remove : (K) -> Unit
  size : () -> Int
}

Related issue:

• render failed should be well handled moon#61.

[skylee03]

Potential breaking change:

• Proposal: migrate Int usage to UInt for some packages core#700: docs/10