summary modules ||the began by introducing the various syntaxes that can be used for importing packagesmodulesand objects inside modules we noted that many programmers only use the import importable syntax so as to avoid name clashesand that we must be careful not to give program or module the same name as top-level python module or directory also discussed were python packages these are simply directories with an __init__ py file and one or more py modules inside them the __init__ py file can be emptybut to support the from importable import syntaxwe can create an __all__ special variable in the __init__ py file set to list of module names we can also put any common initialization code in the __init__ py file it was noted that packages can be nested simply by creating subdirectories and having each of these contain its own __init__ py file two custom modules were described the first just provided few functions and had very simple doctests the second was more elaborate with its own exceptionsthe use of dynamic function creation to create function with platform-specific implementationprivate global dataa call to an initialization functionand more elaborate doctests about half the was devoted to high-level overview of python' standard library several string handling modules were mentioned and couple of io stringio examples were presented one example showed how to write text to file using either the built-in print(function or file object' write(methodand how to use an io stringio object in place of real file in previous we handled command-line options by reading sys argv ourselvesbut in the coverage of the library' support for command-line programming we introduced the optparse module which greatly simplifies command-line argument handling--we will use this module extensively from now on mention was made of python' excellent support for numbersand the library' numeric types and its three modules of mathematical functionsas well as the support for scientific and engineering mathematics provided by the scipy project both library and third-party date/time handling classes were briefly described and examples of how to obtain the current date/time and how to convert between datetime datetime and the number of seconds since the epoch were shown also discussed were the additional collection data types and the algorithms for working with ordered sequences that the standard library providesalong with some examples of using the heapq module' functions the modules that support various file encodings (besides character encodingswere discussedas well as the modules for packing and unpacking the most popular archive formatsand those that have support for audio data an example showing how to use the base encoding to store binary data in py files was givenand also program to unpack tarballs considerable support is provided