read and return text file with def function

i want to input the file name in this case books.txt and get the lines but i cant get it work, i have the files in the same directory but when i run this nothing happens, any way to fix this? or to call that function in another .py file

books.txt

7,1,2,3,4,3
2,6,1,3,1

file_name = input("type the file name: ")
def read_txt(file_name)
    file = open(file_name, "r")
    lines = file.readlines()
    file.close()
    return lines

read_txt(file_name)

but this return nothing and i dont know what to do :(

Answer

You need to add this line to the end, so it actually prints out the values:

print(read_txt(file_name))

So the full code would be (I also changed some code as the OP said what to change):

file_name = input("type the file name: ")
def read_txt(file_name):
    file = open(file_name, "r")
    lines = [x for i in file.readlines() for x in list(map(int, i.strip().split(',')))]
    file.close()
    return lines
print(read_txt(file_name))

Output:

[7, 1, 2, 3, 4, 3 2, 6, 1, 3, 1]