input and output please send back my %(item) or pay me $%(amount) sincerely yoursjoe python user ""print form 'name''mr bush''item''blender''amount' this produces the following outputdear mr bushplease send back my blender or pay me $ sincerely yoursjoe python user the format(method is more modern alternative that cleans up some of the previous code for exampleform """dear {name}please send back my {itemor pay me {amount: fsincerely yoursjoe python user ""print form format(name='mr bush'item='blender'amount= for certain kinds of formsyou can also use template stringsas followsimport string form string template("""dear $nameplease send back my $item or pay me $amount sincerely yoursjoe python user """print form substitute({'name''mr bush''item''blender''amount'"% }in this casespecial variables in the string indicate substitutions the form substitute(method takes dictionary of replacements and returns new string although the previous approaches are simplethey aren' always the most powerful solutions to text generation web frameworks and other large application frameworks tend to provide their own template string engines that support embedded control-flowvariable substitutionsfile inclusionand other advanced features generating output working directly with files is the / model most familiar to programmers howevergenerator functions can also be used to emit an / stream as sequence of data fragments to do thissimply use the yield statement like you would use write(or print statement here is an examplef lib fl ff