norepeat

def norepeat(string):
 # @param string: str
 # @return str
  for i in range(len(string)):
   if string[i] != '*' and string[i]!= ' ':
    sost=string[i]
    for j in range(i+1,len(string)):
      if string[j] == sost:
       string=string[0:j]+ '*' + string[j+1:len(string)]
  return string