'Called when the player releases a key. See pyglet docs for key
mappings.
Parameters
symbol : int
Number representing the key that was pressed.
modifiers : int
Number representing any modifying keys that were pressed.'

def on_key_release(self, symbol, modifiers):

    if (symbol == key.W):
        self.strafe[0] += 1
    elif (symbol == key.S):
        self.strafe[0] -= 1
    elif (symbol == key.A):
        self.strafe[1] += 1
    elif (symbol == key.D):
        self.strafe[1] -= 1
