python programming help, im trying to save the scan into a file which allows the user to choose the file name?

hi this is my code i want to save the file after the scan is finish into a txt file, can anyone help please

#!/usr/bin/python

#Color For Terminal

r = '\033[31m' #red

b = '\033[34m' #blue

g = '\033[32m' #green

print g + "hello there"

print ""

print b+ "##################################################"

print "# quicksnap - A Customized Nmap Automatic Scanner#"

print "##################################################"

print ""

print r+ "Scanning Options"

print "[1] Intense Scan"

print "[2] Intense Scan + UDP"

print "[3] Intense Scan - all TCP ports"

print "[4] Intense Scan w/out ping"

print "[5] Ping Scan"

print "[6] Quickie Scan"

print "[7] Quick Traceroute"

print "[8] Normal Scan"

print "[9] Send Bad Checksums"

print "[10] Generate Randon Mac Adress Spoofing for Evasion"

print "[11] Fragment Packets"

print "[12] Check for Possible Vulnerabilities"

option = raw_input("Choose your Scanning Option:")

print g+ ""

if option == '1':

ip = raw_input("Input IP Address / Hostname:")

os.system("nmap -T4 -A -v "+ip)

elif option == '2':

ip = raw_input("Input IP Address / Hostname:")

os.system("nmap -sS -sU -T4 -A -v "+ip)

elif option == '3':

ip = raw_input("Input IP Address / Hostname:")

os.system("nmap -p 1-65535 -T4 -A -v "+ip)

elif option == '4':

ip = raw_input("Input IP Address / Hostname:")

os.system("nmap -T4 -A -v -Pn "+ip)

elif option == '5':

ip = raw_input("Input IP Address / Hostname:")

os.system("nmap -sn "+ip)

elif option == '6':

ip = raw_input("Input IP Address / Hostname:")

os.system("nmap -T4 -F "+ip)

elif option == '7':

ip = raw_input("Input IP Address / Hostname:")

os.system("nmap -sn --traceroute "+ip)

elif option == '8':

ip = raw_input("Input IP Address / Hostname:")

elif option == '9':

ip = raw_input("Input IP Address / Hostname:")

os.system("nmap --badsum "+ip)

elif option == '10':

ip = raw_input("Input IP Address / Hostname:")

os.system("nmap -sT -Pn --spoofmac 0 "+ip)

elif option == '11':

ip = raw_input("Input IP Address / Hostname:")

os.system("nmap -f "+ip)

elif option == '12':

ip = raw_input("Input IP Address / Hostname:")

os.system("nmap --script vuln "+ip)

else:

print b+ "Your Choice is Invalid"

print "Goodbye"

name_of_file = raw_input("write file name: ")

completeName = name_of_file + ".txt"