raising exceptions raising instances signaling conditions with version considerations random module about generator example range built-in function counter loops iteration and list comprehensions and loop coding techniques and - nonexhaustive traversals sequence scans sequence shufflers timing calls example rapid development cycle rational numbers raw_input built-in function re module about findall function match function pattern matching and search function read-only descriptors recursive comparisons recursive functions about coding alternatives from statement and generators and handling arbitrary structures - loops versus reloaders - summation with usage examples reduce built-in function reference counters references (see also shared referencesabout assignments and attribute circular copies versus - cyclic dynamic typing and - index string method calls weak relative imports model about - absolute imports versus lookup rules summary pitfalls of - scope of usage considerations - usage examples - version considerations reload built-in function about - - common usage mistakes from statement and - usage examples - repetition as programming pillar in strings in tuples usage considerations repr built-in function about display formats string formatting method calls and version considerations __repr__ method about - custom print displays inheritance and print display example - recursive looping and reserved words restructuredtext markup language return statement about coding functions function gotchas returning multiple values yield statement versus - reversed built-in function rias (rich internet applications) rich internet applications (rias) __rmod__ method round built-in function running programs (see program executions sax parsing