preopened file objects in the sys modulesuch as sys stdout (see "print operationson page in for detailsdescriptor files in the os module integer file handles that support lower-level tools such as file locking (see also the "xmode in python ' open for exclusive creationsocketspipesand fifos file-like objects used to synchronize processes or communicate over networks access-by-key files known as "shelvesused to store unaltered and pickled python objects directlyby key (used in shell command streams tools such as os popen and subprocess popen that support spawning shell commands and reading and writing to their standard streams (see and for examplesthe third-party open source domain offers even more file-like toolsincluding support for communicating with serial ports in the pyserial extension and interactive programs in the pexpect system see applications-focused python texts and the web at large for additional information on file-like tools version skew notein python xthe built-in name open is essentially synonym for the name fileand you may technically open files by calling either open or file (though open is generally preferred for openingin python xthe name file is no longer availablebecause of its redundancy with open python users may also use the name file as the file object typein order to customize files with object-oriented programming (described later in this bookin python xfiles have changed radically the classes used to implement file objects live in the standard library module io see this module' documentation or code for the classes it makes available for customizationand run type(fcall on an open file for hints core types review and summary now that we've seen all of python' core built-in types in actionlet' wrap up our object types tour by reviewing some of the properties they share table - classifies all the major types we've seen so far according to the type categories introduced earlier here are some points to remembercore types review and summary