What happens when from a string slice you skip the start and/or end values of the slice?

What would the following expressions return?

1. "Hello World".upper( ).lower( )
2. "Hello World".lower( ).upper( )
3. "Hello World".find("Wor", 1, 6)
4. "Hello World".find("Wor")
5. "Hello World".find("wor")
6. "Hello World".isalpha( )
7. "Hello World".isalnum( )
8. "1234".isdigit( )
9. "123FGH".isdigit( )

Try to find out if for any case, the string functions isalnum( ) and isalpha( ) return the same result

Suggest appropriate functions for the following tasks:

1. To check whether the string contains digits
2. To find for the occurrence a string within another string
3. To convert the first letter of a string to upper case
4. to capitalize all the letters of the string
5. to check whether all letters of the string are in capital letters
6. to remove from right of a string all string-combinations from a given set of letters
7. to remove all white spaces from the beginning of a string