code: def replace(s, old, new, maxreplace=-1):
      
      return s.replace(old, new, maxreplace)
docs: replace (str, old, new[, maxreplace]) -> string
  
      Return a copy of string str with all occurrences of substring
      old replaced by new. If the optional argument maxreplace is
      given, only the first maxreplace occurrences are replaced.