s represent a file that cannot be read, written or seeked. Even though IOBase does not declare read or write because their signatures will vary, implementations and clients should consider those methods part of the interface. Also, implementations may raise UnsupportedOperation when operations they do not support are called. The basic type used for binary data read from or written to a file is bytes. Other bytes-like objects are accepted as method arguments too. Text I/O classes work with str data. Note that calling any method (even inquiries) on a closed stream is undefined. Implementations may raise OSError in this case. IOBase (and its subclasses) support the iterator protocol, meaning that an IOBase object can be iterated over yielding the lines in a stream. IOBase also supports the :keyword:`with` statement. In this example, fp is closed after the suite of the with statement is complete: with open('spam.txt', 'r') as fp: fp.write('Spam and eggs!') c