title: What does "from ... import ..." mean?
body: <pre><code>from sys import argv
  from os.path import exists
  
  script, from_file, to_file = argv
  
  print "Copying from %s to %s" % (from_file, to_file)
  
  # we could two on one line too, how?
  input = open(from_file)
  indata = input.read()
  
  print "The input file is %d bytes long" % len(indata)
  print "Does the output file exist? %r" % exists(to_file)
  print "Ready, hit return to continue, CTRL-C to abort."
  
  raw_input()
  
  output = open(to_file, 'w')
  output.write(indata)
  
  print "Alright, all done."
  
  output.close()
  input.close()
  </code></pre>
  
  <p>On the first two lines I have some idea of what is going on, but want to make sure I fully understand it, as this seems like it might be important.</p>