Python-сообщество

 import re
space_pat = re.compile(r'\s{2,}')
print(space_pat.sub(' ','This string  inсludes extra  spaces'))

 s = input()
print(s.strip())

 a = input('Enter string')
print((' ').join(word for word in a.split(' ') if word != ''))

  
>>> s = '  abc  def  ghi  '
>>> out = ' '.join(s.split())
>>> out
'abc def ghi'
>>>

 b="  bb        ".strip()
print(b)

 >>>beatles = ["John", "Paul", "Ringo", "George"]
>>> s = ", ".join(beatles[:-1]) + " & " + beatles[-1] + "."
>>> print(s)
John, Paul, Ringo & George.
>>> 

 beatles = ["John"]