title: get packet size in scapy / python
body: <p>In Scapy (or even just Python, for that sake), how do I get the size in bytes of a given packet?
  I'm tempted to use the function <code>len</code> but I'm not sure what exactly it returns in the case of packets.</p>
  
  <pre><code>&gt;&gt;&gt; len(IP(dst="www.google.com"))
  20
  
  &gt;&gt;&gt; len(IP(dst="www.google.com")/TCP(dport=80))
  40
  </code></pre>