Replacement in the line of double space for a single

I have a line:

   str  =  'a l a m a k o t a '  

as can be seen in the line, between the letters of the same word I have one gap, between the words two. Class = ""> 'Ala ma kota'

I tried to decide, but crashed:

I used to change double gaps to '`' ':

   for  i  in   range  ( len  ( str )- 1 ):   if   str  [i] ==  ''   and   str  [i+ 1 ] ==  '' :  comment.replace ( 'str [i]' ,  '' ')  comment.Replace (' 'str [i + 1]' ,  '`' ')     
 Then I remove the single: 
  
   str . CroupLace ( '' ,  '' )     
 and at the end I replace '`' 'with a gap: 
  
   str . Class = ""> '' `'' ,  '' ')     
 But this whole design does not work. How can this problem solve?