How to use the bluesky.stack.stack function in bluesky

rwykey = name[8:10]
                if not name[10].isidigit():
                    rwykey = rwykey+name[10]
            # also if it is only RW
            else:
                rwykey = name[7:9]
                if not name[9].isidigit():
                    rwykey = rwykey+name[9]

            wphdg = bs.navdb.rwythresholds[name[:4]][rwykey][2]

            # keep constant runway heading
            stack.stack("HDG " + str(bs.traf.id[self.iac]) + " " + str(wphdg))

            # start decelerating
            stack.stack("DELAY " + "10 " + "SPD " + str(bs.traf.id[self.iac]) + " " + "10")

            # delete aircraft
            stack.stack("DELAY " + "42 " + "DEL " + str(bs.traf.id[self.iac]))

            return self.wplat[self.iactwp],self.wplon[self.iactwp],   \
                           self.wpalt[self.iactwp],self.wpspd[self.iactwp],   \
                           self.wpxtoalt[self.iactwp],self.wptoalt[self.iactwp], \
                           self.wpxtorta[self.iactwp], self.wptorta[self.iactwp], \
                           lnavon,self.wpflyby[self.iactwp], nextqdr

        lnavon = self.iactwp +1 < self.nwp
        if lnavon:
            self.iactwp += 1

        nextqdr = self.getnextqdr()

def update(self):

        # First time: IC window in pygame version
        if self.firstx:
            stack.stack("IC")
            self.firstx = False

        # Get events
        for event in pg.event.get():
            if event.type==pg.QUIT:
                bs.sim.stop()

            elif event.type==pg.KEYDOWN:

                # Alphanumeric key
                if event.key>31 and event.key<127:
                    bs.scr.editwin.insert(str(event.str).upper())

                elif event.key==13: # ENTER
                    cmdline = bs.scr.editwin.getline()
                    bs.scr.editwin.enter()

% (self.year, self.month, self.day, self.hour)

        # first clear exisiting wind field
        stack.stack('DEL wind')

        # add new wind field
        data = self.extract_wind(grb, self.lat0, self.lon0, self.lat1, self.lon1)
        df = pd.DataFrame(data.T, columns=['lat','lon','alt','vx','vy'])
        df['dir'] = np.degrees(np.arctan2(df.vx, df.vy))
        df['spd'] = np.sqrt(df.vx**2 + df.vy**2)

        for (lat, lon), d in df.groupby(['lat', 'lon']):
            cmd = "WIND %d,%d," % (lat, lon)
            for idx, r in d.iterrows():
                cmd += "%d,%d,%d," % (r.alt, r.dir, r.spd)
            stack.stack(cmd)

        return True, "Wind field update in area [%d, %d], [%d, %d]. " \
            % (self.lat0, self.lat1, self.lon0, self.lon1) \
            + "time: %04d-%02d-%02d %02d:00" \
            % (self.year, self.month, self.day, self.hour)

def remove_outdated_ac(self):
        """House keeping, remove old entries (offline > 100s)"""
        for addr, ac in list(self.acpool.items()):
            if 'ts' in ac:
                # threshold, remove ac after 90 seconds of no-seen
                if (int(time.time()) - ac['ts']) > 100:
                    del self.acpool[addr]
                    # remove from sim traffic
                    if 'callsign' in ac:
                        stack.stack('DEL %s' % ac['callsign'])
        return

def setspd(self,cmdargs):
        if len(cmdargs)==1:
            spd = txt2spd(cmdargs[0])
            self.startspdmin = spd
            self.startapdmax = spd
        elif len(cmdargs)>1:
            spd0,spd1 = txt2spd(cmdargs[0]),txt2spd(cmdargs[1])
            self.startspdmin = min(spd0,spd1)
            self.startspdmax = max(spd0,spd1)
        else:
            stack.stack("ECHO "+self.name+" SPD "+str(self.startaltmin)+" "+str(self.startaltmax))

#stack.stack(acid + " ADDWPT ",wplat," ",wplon)
                    #stack.stack(acid+"LNAV ON")
                    if idest>=0:
                        if self.dest[idest][:4] != "SEGM":
                            stack.stack(acid + " DEST " + self.dest[idest])
                        else:
                            stack.stack(acid + " DEST " + str(self.destlat[idest])
                                    + " " + str(self.destlon[idest]))

                    if self.name[:4] != "SEGM":
                        stack.stack(acid + " ORIG " + self.name)
                    else:
                        stack.stack(acid + " ORIG " + str(self.lat) + " " + str(self.lon))

                    stack.stack(acid + " SPD 250")
                    stack.stack(acid + " ALT FL100")
                    stack.stack(acid + " HDG " + str(self.rwyhdg[i]))

                    stack.stack(acid+" LNAV OFF")

            # Not runway, then define instantly at position with random heading or in case of segment inward heading
            if gennow:
                if not self.incircle:
                    lat,lon = kwikpos(ctrlat,ctrlon,self.segdir,radius)
                    hdg = self.segdir-180
                elif self.type=="seg":
                    lat,lon,brg = getseg(self.name)
                    hdg = (brg+180)%360
                elif self.type=="rwy":
                    lat,lon = self.lat,self.lon
                    hdg     = self.hdg # Runway heading
                else:

def toggle(self, flag=None):
        if flag:
            self.connected = True
            stack.stack('OP')
            return True, 'Connecting to OpenSky'
        else:
            self.connected = False
            return True, 'Stopping the requests'

for event in pg.event.get():
            if event.type==pg.QUIT:
                sim.stop()

            elif event.type==pg.KEYDOWN:

                # Alphanumeric key
                if event.key>31 and event.key<127:
                    scr.editwin.insert(str(event.unicode).upper())

                elif event.key==13: # ENTER
                    cmdline = scr.editwin.getline()
                    scr.editwin.enter()
                    if len(cmdline)>0:
                        self.lastcmd = cmdline
                        stack.stack(cmdline)

                elif event.key==8:   # BACKSPACE
                    scr.editwin.backspace()

                elif event.key==27: # ESCAPE
                    sim.stop()

                elif event.key ==pg.K_F3: # F3: Insert last command
                    scr.editwin.insert(self.lastcmd.strip().upper()+" ")
                   
                # Display keys
                elif event.key == 269: # Num lock minus
                    stack.stack("ZOOM OUT")
                elif event.key == 270: # Num lock pluus
                    stack.stack("ZOOM IN")