docs: def _get_unique_common_encodes():
      """
      This function will return both unique_encodes and common_encodes as tuple.
  
      unique_encodes : In dictionary with encodes name as key and its
         corresponding encode's unique characters among other available encodes.
      common_encodes : In set type which has all common encode compound
         characters from all available encodes.
         i.e. removed common encode single characters
  
      Author : Arulalan.T
  
      04.08.2014
  
      """
  
      _all_unique_encodes_ = []
      _all_unicode_encodes_ = {}
      _all_common_encodes_ = set([])
      _all_common_encodes_single_char_ = set([])
  
      for name, encode in _all_encodes_.items():
          encode_utf8 = set([PYTHON3 and ch or ch.decode( 'utf-8') for ch in encode.keys()])
          _all_unicode_encodes_[name] = encode_utf8
      _all_unique_encodes_full_ =_all_unicode_encodes_.copy()
  
      for supname, super_encode in _all_unicode_encodes_.items():
          for subname, sub_encode in _all_unicode_encodes_.items():
              if supname == subname: continue
              # get unique of super_encode among other encodings
              super_encode = super_encode - sub_encode
          # get common for all over encodings
          common = _all_unique_encodes_full_[supname] - super_encode
          # merge common to all encodings common
          _all_common_encodes_ = _all_common_encodes_.union(common)
          # store super_encode's unique keys with its name
          _all_unique_encodes_.append((supname, super_encode))
      for ch in _all_common_encodes_:
          # collect single common chars
          if len(ch) == 1: _all_common_encodes_single_char_.add(ch)
      # end of for ch in _all_common_encodes_:
  
      # remove single common char from compound common chars
      _all_common_encodes_ -= _all_common_encodes_single_char_
  
  
      if __WRITE_CHARS_TXT:
          # write common compound characters of all encodes
          f = open('all.encodes.common.chars.txt', 'w')
          for ch in _all_common_encodes_:
              ch = ch.encode('utf-8')
              for encode_keys in _all_encodes_.values():
                  if ch in encode_keys:
                      uni = encode_keys[ch]
                      break
                  # end of if ch in encode_keys:
              # end of for encode_keys in _all_encodes_.values():
              f.write(ch + '  =>  ' + uni + '\n')
          # end of for ch in _all_common_encodes_:
          f.close()
          # write unique compound characters of all encodes
          for encode_name, encode_keys in _all_unique_encodes_:
              f = open(encode_name + '.unique.chars.txt', 'w')
              for ch in encode_keys:
                  ch = ch.encode('utf-8')
                  uni = _all_encodes_[encode_name][ch]
                  f.write(ch + '  =>  ' + uni + '\n')
              # end of for ch in encode_keys:
              f.close()
          # end of for encode_name, encode_keys in _all_unique_encodes_:
      # end of if __WRITE_CHARS_TXT:
  
      return (_all_unique_encodes_, _all_common_encodes_)