some notes:
1. strings are immutable. for ex. you have to assign it to a list, change the list, and join back to a string. or use bytearray()
2. tuples are immutable. they are not used as often as lists in practice, but their immutability is the whole point when used.
3. use dir() and help() to find how to use an object/type
4. lists are positionally ordered collections of arbitrarily types objects, not necessarily homogeneuous, and they have no fixed size. they are mutable.
5. core data types support arbitrary nesting -- we can nest them in any combination, and as deeply as you like.
6. list comprehension expression is very powerful way to process sequence structures, example:
d=[c*2 for c in 'world']
related tools are map and filter.
7. Dictionaries are mappings from keys to values. use d={} to init dictionaries.
8. missing keys test: if not 'f' in d.
9. sorting keys in map: for key in sorted(d)
10. File objects are the main interface to external files on computer.
11. Binary Bytes files and Unicode text files.
12. sets are created like X=set('hello') or Y={'a',b','c'}. they are unordered collection of unique and immutable objects. it supports set operations as in set theory.
13. user defined classes