>>> s = 'yuanzhumuban'

>>> s.capitalize()

'yuanzhumuban'

>>> s = 'my name is yuanzhumuban, age is 20'

>>> s

'my name is yuanzhumuban, age is 20'

>>> s.replace( '20', '30' )

'my name is yuanzhumuban, age is 30'

>>> s

'my name is yuanzhumuban, age is 20'

>>>

>>> help( str.replace )　   

replace(...)

S.replace(old, new[, count]) -> string

Return a copy of string S with all occurrences of substring

old replaced by new. If the optional argument count is

given, only the first count occurrences are replaced.

 str = '121212'

str.replace( '1', 'g' )

 'g2g2g2'

 str.replace( '1', 'g', 1 )

 'g21212'

str.replace( '1', 'g', 2 )

 'g2g212'

str.replace( '1', 'g', 3 )

 'g2g2g2'

 1 >>> ip='127.0.0.1'

 2 >>> ip

 3 '127.0.0.1'

 4 >>> ip.split( '.' )

 5 ['127', '0', '0', '1']

 6 >>> ip.split( '.', 1 )

 7 ['127', '0.0.1']

 8 >>> ip.split( '.', 2 )

 9 ['127', '0', '0.1']

10 >>> ip.split( '.', 3 )

11 ['127', '0', '0', '1']

12 >>>

1 >>> import string

2 >>> help( string.capitalize )

3

4 >>> s = 'ghostwu'

5 >>> string.capitalize( s )

6 'Ghostwu'

1 >>> import string

 2 >>> s = 'my name is ghostwu, age is 20'

 3 >>> string.replace( s, '20', '30' )

 4 'my name is ghostwu, age is 30'

 5 >>> ip

 6 '127.0.0.1'

 7 >>> string.split( ip, '.' )

 8 ['127', '0', '0', '1']

 9 >>> string.split( ip, '.', 1 )

10 ['127', '0.0.1']

11 >>>