1f = open("io/data/file1")
2print(f.readline())
3print(f.readline(3))
4print(f.readline(4))
5print(f.readline(5))
6print(f.readline())
7
8# readline() on writable file
9f = open("io/data/file1", "ab")
10try:
11    f.readline()
12except OSError:
13    print("OSError")
14f.close()
15