title: how to check packet type is tcp syn or rst in pox controller
body: <p>Here is the code</p>
  
  <pre><code>import pox.lib.packet as pkt
  from pox.lib.packet import *
  def _handle_PacketIn(self,event):
    packet=event.parsed
    if packet.type == pkt.IP_TYPE:
      ip_packet = packet.payload
      if ip_packet.protocol == pkt.TCP_PROTOCOL:
        tcp_packet = ip_packet.payload
      if &lt;condition to check packet is TCP SYN or ACK or RST&gt;: 
  </code></pre>
  
  <ol>
  <li>what shoud be the expression within if to check whether that TCP packet is SYN/ACK/RST?</li>
  </ol>