code: def chars2str(chars) -> List[str]:
      
      strings = collections.deque()
      for subchars in chars:
          substrings = collections.deque()
          for char in subchars:
              if char:
                  substrings.append(char.decode('utf-8'))
              else:
                  substrings.append('')
          strings.append(''.join(substrings))
      return list(strings)
docs: Inversion function of function |str2chars|.
  
      >>> from hydpy.core.netcdftools import chars2str
  
      >>> chars2str([[b'z', b'e', b'r', b'o', b's'],
      ...            [b'o', b'n', b'e', b's', b'']])
      ['zeros', 'ones']
  
      >>> chars2str([])
      []