Create an instance from a dict.

        An alternative constructor. Equivalent to ``DidlObject(**content)``.

        Args:
            content (dict): a dict containing metadata information. Required.
                Valid keys are the same as the parameters for `DidlObject`.

def from_dict(cls, content):
        """Create an instance from a dict.

        An alternative constructor. Equivalent to ``DidlObject(**content)``.

        Args:
            content (dict): a dict containing metadata information. Required.
                Valid keys are the same as the parameters for `DidlObject`.

        """
        # Do we really need this constructor? Could use DidlObject(**content)
        # instead.  -- We do now
        if 'resources' in content:
            content['resources'] = [DidlResource.from_dict(x)
                                    for x in content['resources']]
        return cls(**content)