# importing argv from module #sys                                                                                                                                                                                                              
from sys import argv

script, filename = argv

print "We're going to erase %r." % filename
print "If you don't want that, hit CTRL-C (^C)."
print "If you do want that, hit RETURN."

# If you hit CTRL-C here, code will not execute further and exit.                                                                                                                                                                             
raw_input("?")

print "Opening the file..."
# if file is not exist, then it will be created, otherwise flush out the content                                                                                                                                                              
# and open it for writing                                                                                                                                                                                                                     
target = open(filename, 'w')

print "Truncating the file.  Goodbye!"
# Method truncate erase the contents of the file from current position to the arg provided.                                                                                                                                                   
# Now current position is start of file.                                                                                                                                                                                                      
# If no arg is provided, then file size is used.                                                                                                                                                                                              
target.truncate()

print "Now I'm going to ask you for three lines."

# reading three lines from std. i/p                                                                                                                                                                                                           
line1 = raw_input("line 1: ")
line2 = raw_input("line 2: ")
line3 = raw_input("line 3: ")

print "I'm going to write these to the file."
# wrting three lines to file                                                                                                                                                                                                                  
target.write(line1)
target.write("\n")
target.write(line2)
target.write("\n")
target.write(line3)
target.write("\n")

print "And finally, we close it."
target.close()