<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def AddKeyByPath(self, key_path, registry_key):
 """Adds a Windows Registry key for a specific key path. Args: key_path (str):
 Windows Registry key path to add the key. registry_key (WinRegistryKey):
 Windows Registry key. Raises: KeyError: if the subkey already exists. ValueError: if the Windows Registry key cannot be added. """

    if not key_path.startswith(definitions.KEY_PATH_SEPARATOR):
      raise ValueError('Key path does not start with: {0:s}'.format(
          definitions.KEY_PATH_SEPARATOR))

    if not self._root_key:
      self._root_key = FakeWinRegistryKey(self._key_path_prefix)

    path_segments = key_paths.SplitKeyPath(key_path)
    parent_key = self._root_key
    for path_segment in path_segments:
      try:
        subkey = FakeWinRegistryKey(path_segment)
        parent_key.AddSubkey(subkey)
      except KeyError:
        subkey = parent_key.GetSubkeyByName(path_segment)

      parent_key = subkey

    parent_key.AddSubkey(registry_key)