Create a Simple Time Calculator (TK)

from tkinter import *

main_window = Tk()
main_window.title("Time Calculation")
main_window.geometry("700x200+200+300")

def getValues(theList):
    val=[]
    for i in theList:
        if i.get():
            val.append(int(i.get()))
        else:
            val.append(0)
    return val
     
def calcTime(theList):
    seconds = theList[3]
    minutes = theList[2]*60
    hours = theList[1]*60*60
    days = theList[0]*24*60*60
    return seconds+minutes+hours+days

def convertTime(timeV):
    timeL=[]
    timeL.append(timeV//86400)
    rem = timeV % 86400
    
    timeL.append(rem//3600)
    rem = rem % 3600  

    
    timeL.append(rem//60)    
    rem = rem % 60
    
    timeL.append(rem)
    return timeL
    
def fillEntries(values,theList):
    for i in range(4):
        theList[i].delete(0,"end")
        theList[i].insert(0,str(values[i]))


first =[]
second = []
third = []

theFrame = Frame(main_window,width=700,height=200)
theFrame.pack(expand=FALSE)
frame1 = Frame(theFrame)
frame1.pack(side=LEFT,pady=20)
frame2 = Frame(theFrame)
frame2.pack(side=RIGHT,pady=20)

frames=[]
for i in range(0,6):
   frames.append(Frame(frame2))
   frames[i].pack()
    
titles=[]
titlesT=["Days","Hours","Minutes","Seconds"]
   
for i in range(0,4):
    titles.append(Label(frames[0],text=titlesT[i]))
    first.append(Entry(frames[0]))
    second.append(Entry(frames[2]))
    third.append(Entry(frames[4],bg="lightgray",fg="green",font=("times",10,"bold")))
    titles[i].grid(row=0,column=i)
    first[i].grid(row=1,column=i)
    second[i].grid(row=0,column=i)
    third[i].grid(row=0,column=i)
    
    
plusLabel=StringVar()
plusLabel.set("+")
plusLabel = Label(frame1,textvariable=plusLabel)
plusLabel.grid(row=2,column=0)

lineC = Canvas(frames[3], width=600,heigh=10)
lineC.create_line(0,5,590,5, fill="black",width=1)

lineC.grid(row=0, column=0)

def calc():
    values1= getValues(first)
    values2= getValues(second)
    t1 = calcTime(values1)
    t2 = calcTime(values2)
    res = t1 + t2
    myValues = convertTime(res)
    fillEntries(myValues,third)
    return 

eqButton = Button(frame1,text="=",command=calc,bg="white")
eqButton.grid(row=4,column=0)

def clearET():
    for i in range(4):
        first[i].delete(0,"end")
        second[i].delete(0,"end")
        third[i].delete(0,"end")
        
        
clButton = Button(frames[5],text="Clear",bg="skyblue",command=clearET)
clButton.grid(row=0,column=0,pady=20)

main_window.mainloop()