docs: def is_pcap(pcap):
      """
      Simple test for pcap magic bytes in supplied file.
  
      :param pcap: File path to Pcap file to check
      :returns: True if content is pcap (magic bytes present), otherwise False.
      """
      with open(pcap, 'rb') as tmp:
          header = tmp.read(4)
          # check for both big/little endian
          if header == b"\xa1\xb2\xc3\xd4" or \
             header == b"\xd4\xc3\xb2\xa1":
              return True
          return False