:returns: The header value as string
:raises: :exc:`NotInitializedError` if the message is not
initialized
- :raises: :exc:`NullPointerError` if any error occured
+ :raises: :exc:`NullPointerError` if any error occurred
"""
if not self._msg:
raise NotInitializedError()
:returns: A :class:`Tags` iterator.
:raises: :exc:`NotInitializedError` if the message is not
initialized
- :raises: :exc:`NullPointerError` if any error occured
+ :raises: :exc:`NullPointerError` if any error occurred
"""
if not self._msg:
raise NotInitializedError()