code: def compile_regex_from_str(self, ft_str):
          
  
          sequence = []
          for m in re.finditer(r'\[([^]]+)\]', ft_str):
              ft_mask = fts(m.group(1))
              segs = self.all_segs_matching_fts(ft_mask)
              sub_pat = '({})'.format('|'.join(segs))
              sequence.append(sub_pat)
          pattern = ''.join(sequence)
          regex = re.compile(pattern)
          return regex
docs: Given a string describing features masks for a sequence of segments,
          return a regex matching the corresponding strings.
  
          Args:
              ft_str (str): feature masks, each enclosed in square brackets, in
              which the features are delimited by any standard delimiter.
  
          Returns:
             Pattern: regular expression pattern equivalent to `ft_str`