docs: def __get_edges_by_vertex(self, vertex, keys=False):
          """ Iterates over edges that are incident to supplied vertex argument in current :class:`BreakpointGraph`
  
          Checks that the supplied vertex argument exists in underlying MultiGraph object as a vertex, then iterates over all edges that are incident to it. Wraps each yielded object into :class:`bg.edge.BGEdge` object.
  
          :param vertex: a vertex object in current :class:`BreakpointGraph` object
          :type vertex: any hashable object. :class:`bg.vertex.BGVertex` object is expected.
          :param keys: a flag to indicate if information about unique edge's ids has to be returned alongside with edge
          :type keys: ``Boolean``
          :return: generator over edges (tuples ``edge, edge_id`` if keys specified) in current :class:`BreakpointGraph` wrapped in :class:`bg.vertex.BGEVertex`
          :rtype: ``generator``
          """
          if vertex in self.bg:
              for vertex2, edges in self.bg[vertex].items():
                  for key, data in self.bg[vertex][vertex2].items():
                      bg_edge = BGEdge(vertex1=vertex, vertex2=vertex2, multicolor=data["attr_dict"]["multicolor"],
                                       data=data["attr_dict"]["data"])
                      if keys:
                          yield bg_edge, key
                      else:
                          yield bg_edge