xgb-keys: minimal example of reading keys
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										213
									
								
								prototypes/xgb-keys.go
									
									
									
									
									
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										213
									
								
								prototypes/xgb-keys.go
									
									
									
									
									
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package main
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import (
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	"github.com/BurntSushi/xgb"
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	//"github.com/BurntSushi/xgb/xkb"
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	"github.com/BurntSushi/xgb/xproto"
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	"log"
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)
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func main() {
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	X, err := xgb.NewConn()
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	if err != nil {
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		log.Fatalln(err)
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	}
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	/*
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		// Use the extension if available, makes better use of state bits.
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		if err := xkb.Init(X); err == nil {
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			if _, err := xkb.UseExtension(X, 1, 0).Reply(); err != nil {
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				log.Fatalln(err)
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			}
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		}
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	*/
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	setup := xproto.Setup(X)
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	screen := setup.DefaultScreen(X)
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	visual, depth := screen.RootVisual, screen.RootDepth
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	// TODO: We should check that we find it, though we don't /need/ alpha here,
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	// it's just a minor improvement--affects the backpixel value.
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	for _, i := range screen.AllowedDepths {
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		for _, v := range i.Visuals {
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			// TODO: Could/should check other parameters.
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			if i.Depth == 32 && v.Class == xproto.VisualClassTrueColor {
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				visual, depth = v.VisualId, i.Depth
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				break
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			}
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		}
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	}
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	mid, err := xproto.NewColormapId(X)
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	if err != nil {
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		log.Fatalln(err)
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	}
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	_ = xproto.CreateColormap(
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		X, xproto.ColormapAllocNone, mid, screen.Root, visual)
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	wid, err := xproto.NewWindowId(X)
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	if err != nil {
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		log.Fatalln(err)
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	}
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	// Border pixel and colormap are required when depth differs from parent.
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	_ = xproto.CreateWindow(X, depth, wid, screen.Root,
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		0, 0, 500, 500, 0, xproto.WindowClassInputOutput,
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		visual, xproto.CwBackPixel|xproto.CwBorderPixel|xproto.CwEventMask|
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			xproto.CwColormap, []uint32{0x80808080, 0,
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			xproto.EventMaskStructureNotify | xproto.EventMaskKeyPress |
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				/* KeymapNotify */ xproto.EventMaskKeymapState, uint32(mid)})
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	title := []byte("Keys")
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	_ = xproto.ChangeProperty(X, xproto.PropModeReplace, wid, xproto.AtomWmName,
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		xproto.AtomString, 8, uint32(len(title)), title)
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	_ = xproto.MapWindow(X, wid)
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	mapping, err := xproto.GetKeyboardMapping(X, setup.MinKeycode,
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		byte(setup.MaxKeycode-setup.MinKeycode+1)).Reply()
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	if err != nil {
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		log.Fatalln(err)
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	}
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	// The order is "Shift, Lock, Control, Mod1, Mod2, Mod3, Mod4, and Mod5."
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	mm, err := xproto.GetModifierMapping(X).Reply()
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	if err != nil {
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		log.Fatalln(err)
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	}
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	// XXX: This seems pointless, the key will just end up switching groups
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	// instead of levels without full XKB handling. Though perhaps it might
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	// at least work as intended when there's only one XKB group.
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	const MODE_SWITCH = 0xff7e
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	var modeSwitchMask uint16
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	for mod := 0; mod < 8; mod++ {
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		perMod := int(mm.KeycodesPerModifier)
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		for _, kc := range mm.Keycodes[mod*perMod : (mod+1)*perMod] {
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			if kc == 0 {
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				continue
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			}
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			perKc := int(mapping.KeysymsPerKeycode)
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			k := int(kc - setup.MinKeycode)
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			for _, ks := range mapping.Keysyms[k*perKc : (k+1)*perKc] {
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				if ks == MODE_SWITCH {
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					modeSwitchMask |= 1 << uint(mod)
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				}
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			}
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		}
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	}
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	for {
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		ev, xerr := X.WaitForEvent()
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		if xerr != nil {
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			log.Printf("Error: %s\n", xerr)
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			return
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		}
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		if ev == nil {
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			return
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		}
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		log.Printf("Event: %s\n", ev)
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		switch e := ev.(type) {
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		case xproto.UnmapNotifyEvent:
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			return
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		case xproto.KeymapNotifyEvent:
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			// e.Keys is a 32 * 8 large bitmap indicating which keys are
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			// currently pressed down. This is sent "after every EnterNotify
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			// and FocusIn" but it also seems to fire when the keyboard layout
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			// changes. aixterm manual even speaks of that explicitly.
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			//
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			// But since changing the effective group involves no changes to
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			// the compatibility mapping, there's nothing for us to do.
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		case xproto.MappingNotifyEvent:
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			// e.FirstKeyCode .. e.Count changes have happened but rereading
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			// everything is the simpler thing to do.
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			mapping, err = xproto.GetKeyboardMapping(X, setup.MinKeycode,
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				byte(setup.MaxKeycode-setup.MinKeycode+1)).Reply()
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			if err != nil {
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				log.Fatalln(err)
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			}
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			// TODO: We should also repeat the search for MODE SWITCH.
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		case xproto.KeyPressEvent:
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			step := int(mapping.KeysymsPerKeycode)
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			from := int(e.Detail-setup.MinKeycode) * step
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			ks := mapping.Keysyms[from : from+step]
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			// Strip trailing NoSymbol entries.
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			for len(ks) > 0 && ks[len(ks)-1] == 0 {
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				ks = ks[:len(ks)-1]
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			}
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			// Expand back to at least 4.
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			switch {
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			case len(ks) == 1:
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				ks = append(ks, 0, ks[0], 0)
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			case len(ks) == 2:
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				ks = append(ks, ks[0], ks[1])
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			case len(ks) == 3:
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				ks = append(ks, 0)
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			}
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			// Other silly expansion rules, only applied to basic ASCII.
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			if ks[1] == 0 {
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				ks[1] = ks[0]
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				if ks[0] >= 'A' && ks[0] <= 'Z' ||
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					ks[0] >= 'a' && ks[0] <= 'z' {
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					ks[0] = ks[0] | 32
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					ks[1] = ks[0] &^ 32
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				}
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			}
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			if ks[3] == 0 {
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				ks[3] = ks[2]
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				if ks[2] >= 'A' && ks[2] <= 'Z' ||
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					ks[2] >= 'a' && ks[2] <= 'z' {
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					ks[2] = ks[2] | 32
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					ks[3] = ks[2] &^ 32
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				}
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			}
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			// We only have enough information to switch between two groups.
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			offset := 0
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			if e.State&modeSwitchMask != 0 {
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				offset += 2
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			}
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			var result xproto.Keysym
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			shift := e.State&xproto.ModMaskShift != 0
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			lock := e.State&xproto.ModMaskLock != 0
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			switch {
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			case !shift && !lock:
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				result = ks[offset+0]
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			case !shift && lock:
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				if ks[offset+0] >= 'a' && ks[offset+0] <= 'z' {
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					result = ks[offset+1]
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				} else {
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					result = ks[offset+0]
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				}
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			case shift && lock:
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				if ks[offset+1] >= 'a' && ks[offset+1] <= 'z' {
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					result = ks[offset+1] &^ 32
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				} else {
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					result = ks[offset+1]
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				}
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			case shift:
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				result = ks[offset+1]
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			}
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			if result <= 0xff {
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				log.Printf("%c (Latin-1)\n", rune(result))
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			} else {
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				log.Println(result)
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			}
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		}
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	}
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}
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