problem solved?
Okay ... so it's impossible!
But I put it up in good faith, the guy that sent it to me said it could be done!!!
The reason it's impossible ... well I'll let others explain:
Think of the graph as the floor plan of a seven roomed house.
Put 'doors' in each 'wall' (line segment).
Take a walk through the house .
Note that for a room with an even number of doors it is possible to
take a walk that passes through each door that begins and ends inside
the room or that begins and ends outside the room.
For a room with an odd number of doors this is not so, if the beginning
of the walk is inside the room and each door is used only once, the end
of the walk will be outside the room and vice versa; if the beginning of
the walk is outside the room and each door is used only once the end
will be inside the room.
The 'seven roomed house' has three 'rooms' with an odd number of doors.
A walk has only one end point , so that even if you start inside one of
them ,outside of the other two, you must end up inside both of the
others which is impossible