code: def build_re_pattern_from_intervals(intervals: IntervalListType) -> BuiltInReType:
      
  
      inner = [f'{chr(lb)}-{chr(ub)}' for lb, ub in intervals]
      joined_inner = ''.join(inner)
      pattern = f'[{joined_inner}]+'
  
      return re.compile(pattern, re.UNICODE)
docs: Convert intervals to regular expression pattern.
  
      :param intervals: Unicode codepoint intervals.