how to smooth out a movement godot code example

Example: godot smooth movement

extends KinematicBody2D
const SPEED = 100.0

func _physics_process(delta):
    var input = Vector2()
    input.x += float(Input.is_action_pressed('ui_right'))
    input.x -= float(Input.is_action_pressed('ui_left'))
    input.y -= float(Input.is_action_pressed('ui_up'))
    input.y += float(Input.is_action_pressed('ui_down'))

    if input.length() != 0:
        input = input.normalized()

    move_and_collide(input * SPEED * delta)