def remove_edges(*edges)
      edges = to_edges(edges).sort{|e1,e2| e2<=>e1}
      edges.each do |edge|
        edge.source.remove_out_edge(edge)
        edge.target.remove_in_edge(edge)
        @edges.delete_at(edge.index)
        edge.index = -1
      end
      @edges.each_with_index {|edge,i| edge.index=i}
      self
    end
def remove_edges(*edges)
      edges = to_edges(edges).sort{|e1,e2| e2<=>e1}
      edges.each do |edge|
        edge.source.remove_out_edge(edge)
        edge.target.remove_in_edge(edge)
        @edges.delete_at(edge.index)
        edge.index = -1
      end
      @edges.each_with_index {|edge,i| edge.index=i}
      self
    end
Removes all edges returned by evaluating the _edges_ selection
 expression.