will first print and then produce the error message nameerrorname 'circleis not defined some python programmers frown upon using this form of import because they believe that it makes code more difficult to read as we have seena module can contain executable statements as well as function definitions typicallythese statements are used to initialize the module for this reasonthe statements in module are executed only the first time module is imported into program on related notea module is imported only once per interpreter session if you start up idleimport moduleand then change the contents of that modulethe interpreter will still be using the original version of the module this can lead to puzzling behavior when debugging you can force the interpreter to reload all imported modules by executing reload(there are lots of useful modules that come as part of the standard python library for exampleit is rarely necessary to write your own implementations of common mathematical or string functions description of this library can be found at files every computer system uses files to save things from one computation to the next python provides many facilities for creating and accessing files here we illustrate some of the basic ones each operating system ( windows and mac oscomes with its own file system for creating and accessing files python achieves operating-system independence by accessing files through something called file handle the code namehandle open('kids'' 'instructs the operating system to create file with the name kidsand return file handle for that file the argument 'wto open indicates that the file is to be opened for writing the following code opens fileuses the write method to write two linesand then closes the file it is important to remember to close the file when the program is finished using it otherwise there is risk that some or all of the writes may not be saved namehandle open('kids'' 'for in range( )name raw_input('enter name'namehandle write(name '\ 'namehandle close(in stringthe character "\is an escape character used to indicate that the next character should be treated in special way in this examplethe string '\nindicates new line character