add micropython demo on bearpi board

board/BearPi_STM32L431RC/KEIL/micropython_basic_demo/scripts/os.py

@@ -0,0 +1,40 @@
+import uos as os
+
+# test mkdir()
+print('{:-^40}'.format('test mkdir'))
+print(os.listdir())
+os.mkdir('test_dir')
+print(os.listdir())
+
+# test file open() and write()
+print('{:-^40}'.format('test write'))
+f = open('test_dir/test_file', 'w')
+f.write("Hello TencentOS-tiny\n")
+print("Hello MicroPython", file=f)
+f.close()
+print(os.listdir('test_dir'))
+
+# test file open() and read()
+print('{:-^40}'.format('test read'))
+f = open('test_dir/test_file', 'r')
+print(f.readlines())
+f.close()
+
+# test 'with' statement and iterator
+print('{:-^40}'.format('test with statement'))
+with open('test_dir/test_file', 'r') as file:
+    for line in file:
+        print(line)
+
+# test rename()
+print('{:-^40}'.format('test rename'))
+os.rename('test_dir', 'test_dir2')
+print(os.listdir())
+print(os.listdir('test_dir2'))
+
+# test unlink()
+print('{:-^40}'.format('test unlink'))
+os.unlink('test_dir2/test_file')
+print(os.listdir('test_dir2'))
+os.unlink('test_dir2')
+print(os.listdir())