Creates edge document.

            :param from_doc Document from which the edge comes
            :param to_doc Document to which the edge goes
            :param edge_data Extra data for the edge

            :returns Document

def create_edge(self, from_doc, to_doc, edge_data={}):
        """
            Creates edge document.

            :param from_doc Document from which the edge comes
            :param to_doc Document to which the edge goes
            :param edge_data Extra data for the edge

            :returns Document
        """

        return Edge.create(
            collection=self,
            from_doc=from_doc,
            to_doc=to_doc,
            edge_data=edge_data
        )