example(get_started): add simple hello world example

examples/get_started/lv_example_get_started_4.py

@@ -0,0 +1,22 @@
+def slider_event_cb(evt):
+    slider = evt.get_target()
+
+    # Refresh the text
+    label.set_text(str(slider.get_value()))
+
+#
+# Create a slider and write its value on a label.
+#
+
+# Create a slider in the center of the display
+slider = lv.slider(lv.scr_act())
+slider.set_width(200)                                              # Set the width
+slider.center()                                                    # Align to the center of the parent (screen)
+slider.add_event_cb(slider_event_cb, lv.EVENT.VALUE_CHANGED, None) # Assign an event function
+
+# Create a label above the slider
+label = lv.label(lv.scr_act())
+label.set_text("0")
+label.align_to(slider, lv.ALIGN.OUT_TOP_MID, 0, -15)               # Align below the slider
+
+