comefrom: <doocs>1763.Longest Nice Substring_1.py
code: def longestNiceSubstring( s: str) -> str:
      n = len(s)
      ans = ''
      for i in range(n):
          lower = upper = 0
          for j in range(i, n):
              if s[j].islower():
                  lower |= 1 << (ord(s[j]) - ord('a'))
              else:
                  upper |= 1 << (ord(s[j]) - ord('A'))
              if lower == upper and j - i + 1 > len(ans):
                  ans = s[i : j + 1]
      return ans
masked: def sample_funcname ( var_0 : str ) -> str :
      var_3 = len ( var_0 )
      var_5 = ''
      for var_7 in range ( var_3 ) :
          var_10 = var_8 = 0
          for var_11 in range ( var_7 , var_3 ) :
              if var_0 [ var_11 ].islower ( ) :
                  var_10 |= 1 << ( ord ( var_0 [ var_11 ] ) - ord ( 'a' ) )
              else :
                  var_8 |= 1 << ( ord ( var_0 [ var_11 ] ) - ord ( 'A' ) )
              if var_10 == var_8 and var_11 - var_7 + 1 > len ( var_5 ) :
                  var_5 = var_0 [ var_7 : var_11 + 1 ]
      return var_5
  