How to create a sphere by arraymesh

I read this tutorial：https://docs.godotengine.org/en/stable/tutorials/content/procedural_geometry/arraymesh.html and create gd script like the tutorial. but i can not see a sphere in camera. Did i do something wrong. this is my code

extends MeshInstance

var rings = 50
var radial_segments = 50
var height = 1
var radius = 1

func _ready():
	var arr = []
	arr.resize(Mesh.ARRAY_MAX)
	var verts = PoolVector3Array()
	var uvs = PoolVector2Array()
	var normals = PoolVector3Array()
	var indices = PoolIntArray()

	var thisrow = 0
	var prevrow = 0
	var point = 0
	
	# Loop over rings.
	for i in range(rings + 1):
		var v = float(i) / rings
		var w = sin(PI * v)
		var y = cos(PI * v)
		
		# Loop over segments in ring.
		for j in range(radial_segments):
			var u = float(j) / radial_segments
			var x = sin(u * PI * 2.0)
			var z = cos(u * PI * 2.0)
			var vert = Vector3(x * radius * w, y, z * radius * w)
			verts.append(vert)
			normals.append(vert.normalized())
			uvs.append(Vector2(u, v))
			point += 1
		
			# Create triangles in ring using indices.
			if i > 0 and j > 0:
				indices.append(prevrow + j - 1)
				indices.append(prevrow + j)
				indices.append(thisrow + j - 1)
				
				indices.append(prevrow + j)
				indices.append(thisrow + j)
				indices.append(thisrow + j - 1)
		
		if i > 0:
			indices.append(prevrow + radial_segments - 1)
			indices.append(prevrow)
			indices.append(thisrow + radial_segments - 1)
			
			indices.append(prevrow)
			indices.append(prevrow + radial_segments)
			indices.append(thisrow + radial_segments - 1)
	
	prevrow = thisrow
	thisrow = point


	arr[Mesh.ARRAY_VERTEX] = verts
	arr[Mesh.ARRAY_TEX_UV] = uvs
	arr[Mesh.ARRAY_NORMAL] = normals
	arr[Mesh.ARRAY_INDEX] = indices
	mesh.add_surface_from_arrays(Mesh.PRIMITIVE_TRIANGLES, arr)

i need your help please,thanks a lot. BR.