I need help $($in Python$)$ with the implementation of dependency$\_$scheduler$\_$cooking$\_$redo method and class AND$\_$OR$\_$Scheduler. My Dependency Scheduler almost works, but is failing a few tests. import networkx as nx # Library for displaying graphs.

import matplotlib.pyplot as

p$.$tt

import random

class DependencyScheduler$($object$)$:

def self$)$:

self.tasks $=$ set$()$

# The successors of a task are the tasks that depend on it$,$ and can

# only be done once the task is completed.

# The predecessors of a task $($set$)$

self.predecessors $=$ defaultdict$($set$)$

self.completed$\_$tasks $={?}^{\text{s}\text{e}\text{t}}()$ # completed tasks

def add$\_$task$($self$,t,$ dependencies$)$:

$""".$Adds a task t'with given dependencies. $"\text{'}."$

# Makes sure we know about all tasks mentioned

assert $t$ not in self.tasks or len$($self$.$predecessors$[$t$])==0,$ "The task was already present."

self.tasks.add$($t$)$

self.tasks.update$($dependencies$)$

# The predecessors are the tasks that need to be done before.

self.predecessors $[$t$]=$ set$($dependencies$)$

# The new task is a successor of its dependencies

for u in dependencies:

def reset$($self$)$:

self.completed$\_$tasks $=$ set$()$

@property

def done$($self$)$:

return self.completed$\_$tasks $==$ self.tasks

def show$($self$)$:

$""".$We use the nx graph to display the graph."".

$g=$ nx$.$DiGraph$()$

g$.$add$\_$nodes$\_$from$($self$.$tasks$)$

hode colges$\_$from$([($u$,$ v$)$ for u in self.tasks for v in self.successors$[$u$]])$

$(\text{'}$green$\text{'}$ if v in self.completed$\_$tasks

else 'red' if v in self.available$\_$tasks

else 'gray'$)$

nx$.$draw$($g$,$ with$\_$labels$=$True, node$\_$color$=$node$\_$colors$)$

p$.$lt$.$show$()$

@property

def uncompleted$($self$)$:

$"""$Returns the tasks that have not been completed

This is a property, so you can say scheduler.uncompleted rather than

scheduler.uncompleted$()"$I$"$

return self.tasks $-$ self.completed$\_$tasks

@property

def available$\_$tasks$($self$)$:

$"".$"Returns the available tasks.

This is just a placeholder; we will let you implement this.".".

return set$()$

def mark$\_$completed$($self$,$ t$)$:

$"1$"Marks that the task $t$ is completed, and returns the set of tasks

that become available as a consequence.

This is just a placeholder, we will let you implement this.""!"

return set$()$

def check$($self$)$:

$"."$We check that if $t$ is a successor of $u,$ then $u$ is a predecessor

of t$.""$

for u in self.tasks

for $t$ in self.successors$[$u$]$:

assert u in self.predecessors$[$t$]$

#@title Implementation of and $.$

def scheduler$\_$available$\_$tasks$($self$)$:

$"""$Returns the set of tasks that can be done in parallel.

A task can be done if all its predecessors have been completed

And of course, we don't return any task that has already been

available$\_$tasks $=$ set$()$

avallable in tasks.