class GradesFile:

# creating a constructor

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

self.$\_\_$filename $=$ filename

# getter for filename

def get$\_$filename$($self$)$:

return self.$\_\_$filename

# setter for filename

def set$\_$filename$($self$,$ filename$)$:

self.$\_\_$filename $=$ filename

# function to calculate average

def calculateAverage$($self$)$:

# using try and except to handle possible exceptions

try:

# opening the file

infile $=$ open$($self$.\_\_$filename, $\text{'}$r$\text{'})$

# initializing the total and count

total $=0$

count $=0$

# using a for loop to read the file

for line in infile:

# converting the line to float and adding it to the total

total $+=$ eval$($line$)$

# incrementing the count

count $+=1$

# calculating the average

average $=$ total $/$ count

# returning the average

return f$\text{'}\{$average:$\mathrm{.}2$f$\}\text{'}$

except IOError:

# printing an error message if the file is not found

print$(\text{'}$Error: File not found'$)$

except ValueError:

print$(\text{'}$Error: Invalid value'$)$

# main function

def main$()$:

# using try and except to handle possible exceptions

try:

# opening the file

file $=$ open$(\text{'}$Grades$.$txt$\text{'},\text{'}$w$\text{'})$

# enter grades until the user enters $-1$

print$(\text{'}$Enter grades, enter $-1$ to quit'$)$

grade $=$ int$($input$(\text{'}$Enter grade: $\text{'}))$ # getting the first grade

# using a while loop to get the grades

while grade $!=-1$:

# writing the grade to the file

file.write$($str$($grade$)+\text{'}$

$\text{'})$

grade $=$ int$($input$(\text{'}$Enter grade: $\text{'}))$

# closing the file

file rlnse$()$

$```$ Modify GradesFile class from Lecture $8$ Assignment. Add a new function called "loadGradesData". The header of this function is def loadGradesData$($self$).$ This function uses a loop to load grades in the file $($defined by $\_$filename attribute of the class$)$ to a list and return the list to the caller. Modify init function to add one more data attribute $"\_\_$gradesList". Inside function, call "loadGradesData" function and assign the returned value to $"\_$gradesList". Modify calculateAverage function to use the data attribute $"\_\_$gradesList" to calculate average grades. Main function remains unchanged.