when runnung adjacencygraphlist.py:

from Edge import Edge

from DirectedGraph import DirectedGraph

from AdjacencyListVertex import AdjacencyListVertex

class AdjacencyListGraph$($DirectedGraph$)$:

def $\_\_$init$\_\_($self$)$:

self.vertices $=[]$

# Creates and adds a new vertex to the graph, provided a vertex with the

# same label doesn't already exist in the graph. Returns the new vertex on

# success, None on failure.

def add$\_$vertex$($self$,$ new$\_$vertex$\_$label$)$:

if new$\_$vertex$\_$label not in $[$vertex$.$get$\_$label$()$ for vertex in self.vertices$]$:

new$\_$vertex $=$ AdjacencyListVertex$($new$\_$vertex$\_$label$)$

self.vertices.append$($new$\_$vertex$)$

return new$\_$vertex

return None

# Adds a directed edge from the first to the second vertex. If the edge

# already exists in the graph, no change is made and False is returned.

# Otherwise the new edge is added and True is returned.

def add$\_$directed$\_$edge$($self$,$ from$\_$vertex, to$\_$vertex$)$:

from$\_$vertex$\_$obj $=$ self.get$\_$vertex$($from$\_$vertex$)$

to$\_$vertex$\_$obj $=$ self.get$\_$vertex$($to$\_$vertex$)$

if from$\_$vertex$\_$obj is None:

from$\_$vertex$\_$obj $=$ self.add$\_$vertex$($from$\_$vertex$)$

if to$\_$vertex$\_$obj is None:

to$\_$vertex$\_$obj $=$ self.add$\_$vertex$($to$\_$vertex$)$

if to$\_$vertex in from$\_$vertex$\_$obj.adjacent:

return False

from$\_$vertex$\_$obj.adjacent.append$($to$\_$vertex$)$

return True

# Returns a list of edges with the specified from$\_$vertex.

def get$\_$edges$\_$from$($self$,$ from$\_$vertex$)$:

from$\_$vertex$\_$obj $=$ self.get$\_$vertex$($from$\_$vertex$)$

if from$\_$vertex$\_$obj is not None:

return $[$Edge$($from$\_$vertex, to$\_$vertex$)$ for to$\_$vertex in from$\_$vertex$\_$obj.adjacent$]$

return $[]$

# Returns a list of edges with the specified to$\_$vertex.

def get$\_$edges$\_$to$($self$,$ to$\_$vertex$)$:

edges $=[]$

for vertex in self.vertices:

if to$\_$vertex in vertex.adjacent:

edges.append$($Edge$($vertex$.$get$\_$label$(),$ to$\_$vertex$))$

return edges

# Returns a vertex with a matching label, or None if no such vertex exists

def get$\_$vertex$($self$,$ vertex$\_$label$)$:

for vertex in self.vertices:

if vertex.get$\_$label$()==$ vertex$\_$label:

return vertex

return None

# Returns True if self graph has an edge from from$\_$vertex to to$\_$vertex

def has$\_$edge$($self$,$ from$\_$vertex, to$\_$vertex$)$:

from$\_$vertex$\_$obj $=$ self.get$\_$vertex$($from$\_$vertex$)$

if from$\_$vertex$\_$obj is not None:

return to$\_$vertex in from$\_$vertex$\_$obj.adjacent

return False

# Returns a list of vertex labels

def get$\_$vertex$\_$labels$($self$)$:

return $[$vertex$.$get$\_$label$()$ for vertex in self.vertices$]$

$,$ I am runnung into this error:

Traceback $($most recent call last$)$:

File $"/$usercode$/$zylab$\_$unit$\_$test$\_$runner.py$",$ line $76,$ in

passed $=$ test$\_$case.test$\_$passed$($writer$)$

File $"/$usercode$/$coding$\_$rooms$\_$unit$\_$tests.py$",$ line $50,$ in test$\_$passed

return test.execute$($test$\_$feedback, GradingALGraph$())$

File $"/$usercode$/$DirectedGraphTest$.$py$",$ line $13,$ in execute

if not command.execute$($test$\_$feedback, graph$)$:

File $"/$usercode$/$Grading$.$py$",$ line $31,$ in execute

Actual: $[\{\text{'},\text{'}.$join$([$vertex$.$get$\_$label$()$ for vertex in vertices$])\}]$

TypeError: sequence item $5$: expected str instance, AdjacencyListVertex found

How can I fix this?

here is adjacentlistvertex.py

from Vertex import Vertex

class AdjacencyListVertex$($Vertex$)$:

# List of vertices adjacent to this vertex. For each vertex V in this list, V is

# adjacent to this vertex, meaning an edge from this vertex to V exists in the graph.

def $\_\_$init$\_\_($self$,$ label$)$:

super$().\_\_$init$\_\_($label$)$

self.adjacent $=[]$