Embeds a document inside this document.

        Arguments:

        - ``rel``: a string specifying the link relationship type of the
          embedded resource. ``rel`` should be a well-known link relation name
          from the IANA registry
          (http://www.iana.org/assignments/link-relations/link-relations.xml),
          a full URI, or a CURIE.
        - ``other``: a ``Document`` instance that will be embedded in this
          document. If ``other`` is identical to this document, this method
          will silently fail.
        - ``wrap``: Defaults to False, but if True, specifies that the embedded
          resource object should be initally wrapped in a JSON array even if it
          is the first embedded resource for the given ``rel``.

        Calling code should use this method to add embedded resources instead
        of modifying ``embedded`` directly.

        This method embeds the given document in this document with the given
        ``rel``. If one or more documents have already been embedded for that
        ``rel``, the new document will be embedded in addition to those
        documents.

def embed(self, rel, other, wrap=False):
        """Embeds a document inside this document.

        Arguments:

        - ``rel``: a string specifying the link relationship type of the
          embedded resource. ``rel`` should be a well-known link relation name
          from the IANA registry
          (http://www.iana.org/assignments/link-relations/link-relations.xml),
          a full URI, or a CURIE.
        - ``other``: a ``Document`` instance that will be embedded in this
          document. If ``other`` is identical to this document, this method
          will silently fail.
        - ``wrap``: Defaults to False, but if True, specifies that the embedded
          resource object should be initally wrapped in a JSON array even if it
          is the first embedded resource for the given ``rel``.

        Calling code should use this method to add embedded resources instead
        of modifying ``embedded`` directly.

        This method embeds the given document in this document with the given
        ``rel``. If one or more documents have already been embedded for that
        ``rel``, the new document will be embedded in addition to those
        documents.

        """

        if other == self:
            return

        embedded = self.o.setdefault(EMBEDDED_KEY, {})
        collected_embedded = CanonicalRels(embedded,
                                           self.curies,
                                           self.base_uri)

        if rel not in collected_embedded:
            if wrap:
                embedded[rel] = [other.as_object()]
            else:
                embedded[rel] = other.as_object()
        else:
            original_rel = collected_embedded.original_key(rel)

            current_embedded = embedded[original_rel]
            if isinstance(current_embedded, list):
                current_embedded.append(other.as_object())
            else:
                embedded[original_rel] = [current_embedded, other.as_object()]

        if not self.draft.automatic_link:
            return

        url = other.url()
        if not url:
            return

        if url in (link.url() for link in self.links.get(rel, [])):
            return

        self.add_link(rel, other, wrap=wrap)