'Step through the NAWS handshake.
Args:
option (list): The incoming NAWS options.'

def negotiate_sizes(self, options):

    if (len(options) == 4):
        width = (options[0] + options[1])
        self.protocol.protocol_flags['SCREENWIDTH'][0] = int(width.encode('hex'), 16)
        height = (options[2] + options[3])
        self.protocol.protocol_flags['SCREENHEIGHT'][0] = int(height.encode('hex'), 16)
