Expected keyword error - Netlogo

Question

I have this code from book Agent-based and individual based-modeling by Railsback chapter 16 but it doesn't work and I don't know why. I am new in NetLogo, the software shows "Expected keyword" in line 22. (create-packs)

breed [dogs dog]
breed [packs pack]
breed [disperser-groups disperser-group]

dogs-own
[
  age
  sex
  status
  my-pack
  my-disperser-group
]

packs-own [pack-members]

disperser-groups-own
[
  sex
  group-members
]

create-packs initial-num-packs
[
  ; set a location and shape just for display
  setxy random-xcor random-ycor
  set shape "box"

  ; create the pack’s dogs
  let num-dogs random-poisson initial-mean-pack-size

  hatch-dogs num-dogs
  [
    ; first, set display variables
    set heading random 360
    fd 1

    ; now assign dog state variables
    ifelse random-bernoulli 0.5
        [set sex "male"]
        [set sex "female"]

    set age random 7
    set-my-status ; a dog procedure that sets
                  ; social status from age
    set my-pack myself ; set dog’s pack to the one
                       ; creating it
  ] ; end of hatch-dogs

    ; Initialize the pack’s agentset that contains its dogs
  set pack-members dogs with [my-pack = myself]

  ; show count pack-members  ; Test output – off for now

  ; now select the alpha dogs
  update-pack-alphas  ; a pack procedure to give the
                      ; pack 2 alphas

] ; end of create-packs

to go

  tick
  if ticks > years-to-simulate [stop]

  ; First, age and status updates
  ask dogs
  [
    set age age + 1
    set-my-status
  ]

  ask packs [update-pack-alphas]

  ; Second, reproduction
  ask packs [reproduce]

  ; Third, dispersal
  ask packs [disperse]

  ; Fourth, mortality
  ask dogs [do-mortality]

  ; Fifth, mortality of collectives
  ask packs [do-pack-mortality]
  ask disperser-groups [if count group-members = 0 [die]]

  ; Sixth, pack formation
  ask disperser-groups [do-pack-formation]

  ; Finally, produce output
  update-output
end

to disperse ; a pack procedure
  ; First, identify the subordinates and stop if none
  let my-subordinates pack-members with
      [status = "subordinate"]
  if not any? my-subordinates [stop]

  ; Now check females
  if count my-subordinates with [sex = "female"] = 1
  [
    if random-bernoulli 0.5
    [
      create-disperser-group-from
             my-subordinates with [sex = "female"]
    ]
  ]

  if count my-subordinates with [sex = "female"] > 1
  [
    create-disperser-group-from
           my-subordinates with [sex = "female"]
  ]

  ; And check males
  if count my-subordinates with [sex = "male"] = 1
  [
    if random-bernoulli 0.5
    [
      create-disperser-group-from
             my-subordinates with [sex = "male"]
    ]
  ]

  if count my-subordinates with [sex = "male"] > 1
  [
    create-disperser-group-from
           my-subordinates with [sex = "male"]
  ]
end ; to disperse

to create-disperser-group-from [some-dogs]
  ; a pack procedure
  ; "some-dogs" is an agentset of the dispersers

  ; First, create a disperser group and put the dogs in it
  hatch-disperser-groups 1
  [
    ; Set disperser group variables
    set group-members some-dogs
    set sex [sex] of one-of some-dogs

    ; Display the group
    set shape "car"
    set heading random 360
    fd 2

    ; Now the disperser group sets the variables of the
    ; dispersing dogs
    ask some-dogs
    [
      set my-disperser-group myself
      set status "disperser"
      set color green

      ; and display them in a line from the disperser group
      move-to my-disperser-group
      set heading [heading] of my-disperser-group
      fd 1 + random-float 2
    ] ; end of ask some-dogs

  ] ; end of hatch-disperser-groups

  ; Finally, remove the dispersers from their former pack
  let dogs-former-pack [my-pack] of one-of some-dogs
  ask dogs-former-pack
  [set pack-members pack-members with
       [status != "disperser"]]

end ; to create-disperser-group-from

Thanks

Answer 1

you need to start a procedure with the word to but you are not allowed to call a procedure create-packs because that's actually a NetLogo command. I don't have the book to hand, but I suspect this is the setup procedure. Add the procedure name in the previous line, probably this:

to setup
  create-packs initial-num-packs

you also need to end each procedure with the word end, which is also missing. Should look like this further down:

end

to go

In the future, do the syntax checking (green tick) at the end of every block of code rather than typing the whole page. That way you have some idea of where the error is and you can compare what you have typed with what's in the book.