python remove whitespace from start of string

1sentence = ' hello  apple'
2sentence.strip()
3>>> 'hello  apple'

1import re
2s = '\n \t this is a string   with a lot of whitespace\t'
3s = re.sub('\s+', '', s)

1'     hello world!    '.strip()
2'hello world!'
3
4
5'     hello world!    '.lstrip()
6'hello world!    '
7
8'     hello world!    '.rstrip()
9'    hello world!'

1>>> "    xyz     ".rstrip()
2'    xyz'

1sentence = ' hello  apple'
2" ".join(sentence.split())
3>>> 'hello apple'
4

1' sss d ssd s'.replace(" ", "")
2# output: 'sssdssds'