code: def Open(self, file_object):
      
      if not file_object:
        raise ValueError('Missing file-like object.')
  
      # Since pysqlite3 does not provide an exclusive read-only mode and
      # cannot interact with a file-like object directly we make a temporary
      # copy. Before making a copy we check the header signature.
  
      file_object.seek(0, os.SEEK_SET)
      data = file_object.read(len(self._HEADER_SIGNATURE))
  
      if data != self._HEADER_SIGNATURE:
        file_object.close()
        raise IOError('Unsupported SQLite database signature.')
  
      with tempfile.NamedTemporaryFile(delete=False) as temp_file:
        self._temp_file_path = temp_file.name
        while data:
          temp_file.write(data)
          data = file_object.read(self._COPY_BUFFER_SIZE)
  
      self._connection = sqlite3.connect(self._temp_file_path)
      self._connection.text_factory = bytes
      self._cursor = self._connection.cursor()
docs: Opens the database file object.
  
      Args:
        file_object (FileIO): file-like object.
  
      Raises:
        IOError: if the SQLite database signature does not match.
        OSError: if the SQLite database signature does not match.
        ValueError: if the file-like object is invalid.