import os

print('Listing filesystem...')
print(os.listdir(), '\n')

print('Write data...')
with open('data.txt', 'w') as f:
    count = f.write('ololo\n')
    print('Write', count, 'bytes')

print('Read data...')
with open('data.txt', 'r') as f:
    print('Data:', f.read())