This is my invoicing program I made for myself to keep track of purchases people made from me. (Yes I know eBay does this for me but I wanted to see what I could make.) Basically it can search the invoice file for a keyword (the invoice number) or lets you enter a new invoice to a file named usb.txt. It is usb.txt because I was selling USB cables at the time.#Invoice Entering Program Ebayprint(Ebay Invoice Program\n)while True:    file = input(Enter 0 to Quit. Enter S to Search The File. Press ENTER to Input new Entries *Case Sensitive*:  )    if file == 0:        print(Exiting Program...)        break    elif file==S:        keyword = input(Enter Invoice Number to Search For: )        look_in = usb.txt        search_file = open(look_in,r)        with open(look_in, r) as search_file:            for line in search_file:                if keyword in line:                    print(line)    else:        Name = input(Enter Buyer Name: )        InNum = input(Enter Ebay Invoice Number: )        Quant = int(input(Enter Amount Bought: ))        Price = Quant * 5        with open(usb.txt, at)as out_file:            out_file.write(                Name: %s || Invoice Number: %s || Quantity: %s || Price:$ %s \n\n % (Name, InNum, Quant, Price))            out_file.close()            print(File edits made)I'm pretty new to python and programming in general. If you have any suggestions on how I could improve it or any ideas to add functionality I'd love to hear it! This was written in python 3.5.1. 
Invoicing Program Python
python;beginner;python 3.x;io;database