1. lower() method--lower method returns string in lower case.
2. upper() method-- upper method returns string in upper case.
3. replace() method--replace method replaces with other string
4. Split() method --splits the string into substrings if it finds instances of the separator.
5. rfind() method --- it will search substring from right to left
6. find() method --It will search substring from left to right
7. index() method --It will search substring from left to right index.
8. rindex() method -- It will search substring from right to left index.
Note: In find method if we did not get the value it wont through any error and print as -1
but in Index method it will through error.
9. split() method: it will split elements into list based on parameter
10.splitlines() : It will do  splitlines