im playing around with godot and decided to try a platformer game
here's what it looks like now: 
extends KinematicBody2D
const SPEED = 500
const GRAVITY = 5000
const JUMP = 1250
var motion = Vector2.ZERO
func _physics_process(delta):
#horizontal movement
var x_input = Input.get_action_strength("ui_right") - Input.get_action_strength("ui_left")
#vertical movement
motion.y += GRAVITY * delta
#jumps
if Input.is_action_just_pressed("ui_up") and is_on_floor():
motion.y = -JUMP
motion = move_and_slide(motion, Vector2.UP)
however, only the up key works, and the left and right keys don't
any solutions?