$```$

$""$Performs a breadth$-$first search starting from the start$\_$node and returns the first node with the given target$\_$value,

or None if no such node is found."""

def bfs$($self$,$ start$\_$node, target$\_$value$)$:

if not self.head:

return None

queue $=$ None

visited $=$ None

start $=$ self.find$\_$node$($start$\_$node$)$

if not start:

return None

queue $=$ Node$($start$.$data$)$

visited $=$ Node$($start$.$data$)$

while queue:

node $=$ queue

queue $=$ queue.next

if node.data $==$ target$\_$value:

return node

edge $=$ self.find$\_$node$($node$.$data$).$edges

while edge:

if not self.$\_$is$\_$visited$($visited$,$ edge.data.data$)$:

visited $=$ Node$($edge$.$data.data, visited$)$

new$\_$node $=$ Node$($edge$.$data.data$)$

new$\_$node.next $=$ queue

queue $=$ new$\_$node

edge $=$ edge.next

return None

$```$