Sure! Here is an implementation of the Timsort algorithm in Lean 4:

```lean
import Lean

def insertionSort {α : Type u} [LT α] (a : Array α) : Array α :=
  let n := a.size
  let a := a.toBuffer
  for i in [1:n] do
    let x := a[i]
    let j := i
    while j > 0 && a[j - 1] > x do
      a[j] := a[j - 1]
      j := j - 1
    a[j] := x
  return a.toArray

def merge {α : Type u} [LT α] (a : Array α) (b : Array α) : Array α :=
  let na := a.size
  let nb := b.size
  let c := Array.mkEmpty (na + nb)
  let i := 0
  let j := 0
  let k := 0
  while i < na && j < nb do
    if a[i] < b[j] then
      c := c.push a[i]
      i := i + 1
    else
      c := c.push b[j]
      j := j + 1
    k := k + 1
  while i < na do
    c := c.push a[i]
    i := i + 1
    k := k + 1
  while j < nb do
    c := c.push b[j]
    j := j + 1
    k := k + 1
  return c

def timsortAux {α : Type u} [LT α] (a : Array α) (minrun : Nat) : Array α :=
  let n := a.size
  let runStack := Std.Stack.mk (List.nil : List (Nat × Bool))
  let i := 0
  while i < n do
    let descending := i + minrun <= n && a[i] > a[i + minrun - 1]
    let j := i + 1
    while j < n && (j - i < minrun || descending == (a[j - 1] > a[j])) do
      j := j + 1
    if descending then
      let lo := i
      let hi := (i + minrun - 1).min (n - 1)
      let r := insertionSort a[lo:hi+1]
      runStack.push (r.size, true)
      i := hi + 1
    else
      let hi := (j - 1).min (n - 1)
      let r := insertionSort a[i:hi+1]
      runStack.push (r.size, false)
      i := hi + 1
    while runStack.size >= 3 do
      let (c₁, b₁) := runStack.peekD
      let (c₂, b₂) := runStack.peek2D
      if b₁ && b₂ && c₁ + c₂ >= runStack.peek3D!.fst then
        runStack.pop2
        let (a₁, a₂) := a.split ((n - c₂).max 0)
        let merged := merge a₁.reverse a₂
        runStack.push (merged.size, true)
        a := merged
      else if (!b₁ && b₂) && (c₁ + c₂ >= runStack.peek3D!.fst) then
        runStack.pop2
        let (a₁, a₂) := a.split ((n - c₂).max 0)
```
spam fails_task lang_mismatch pii not_appropriate hate_speech sexual_content quality toxicity humor helpfulness creativity violence