diff --git a/_G.yml b/_G.yml
index 0f0e5a9..110388b 100644
--- a/_G.yml
+++ b/_G.yml
@@ -1,212 +1,236 @@
-__root__: &t0x6f478
- _VERSION: Lua 5.2
- add_zeros: f0x73838
- assert: f0x1fefc
- collectgarbage: f0x1f930
- dofile: f0x1fe7c
- dump: f0x78770
- error: f0x1f8c0
- getaddr: f0x74c40
- getmetatable: f0x1fe2c
- ipairs: f0x1fd24
- load: f0x1ff54
- loadfile: f0x1fd80
- loadstring: f0x1ff54
- mixed_sorter: f0x76c28
- module: f0x6fe20
- next: f0x1f7ac
- opairs: f0x74c88
- order_keys: f0x74cd0
- pairs: f0x1fd04
- pcall: f0x1fb50
- print: f0x1f66c
- rawequal: f0x1f62c
- rawget: f0x1f598
- rawlen: f0x1f5d8
- rawset: f0x1f54c
- rawstr: f0x76460
- require: f0x70b00
- select: f0x1f444
- setmetatable: f0x1fbc0
- strpad: f0x73e60
- tonumber: f0x1f25c
- tostring: f0x1f234
- type: f0x1f1f8
- unpack: f0x26598
- xpcall: f0x1fa84
- _G: *t0x6f478
- arg: &t0x736b8
-  "-1": /usr/bin/lua
-  0: ./run.lua
- bit32: &t0x70190
-  arshift: f0x2022c
-  band: f0x20458
-  bnot: f0x20208
-  bor: f0x204c4
-  btest: f0x20434
-  bxor: f0x20478
-  extract: f0x203a4
-  lrotate: f0x20510
-  lshift: f0x20190
-  replace: f0x20338
-  rrotate: f0x201c4
-  rshift: f0x2015c
- coroutine: &t0x6f998
-  create: f0x20844
-  resume: f0x20934
-  running: f0x20824
-  status: f0x206cc
-  wrap: f0x20888
-  yield: f0x20584
- debug: &t0x717c8
-  debug: f0x20e44
-  gethook: f0x21470
-  getinfo: f0x21674
-  getlocal: f0x2132c
-  getmetatable: f0x20d88
-  getregistry: f0x209fc
-  getupvalue: f0x20aac
-  getuservalue: f0x20e0c
-  sethook: f0x2118c
-  setlocal: f0x21094
-  setmetatable: f0x20ab4
-  setupvalue: f0x20a8c
-  setuservalue: f0x20b58
-  traceback: f0x20ff8
-  upvalueid: f0x20ca0
-  upvaluejoin: f0x20cd8
- io: &t0x70fe8
-  close: f0x21c94
-  flush: f0x22328
-  input: f0x22a28
-  lines: f0x22a44
-  open: f0x22b64
-  output: f0x22a0c
-  popen: f0x2238c
-  read: f0x222dc
-  stderr: file (0x76e4f9d8)
-  stdin: file (0x76e4fc98)
-  stdout: file (0x76e4fb38)
-  tmpfile: f0x22c70
-  type: f0x22890
-  write: f0x21ba8
- math: &t0x72a10
-  abs: f0x22e48
-  acos: f0x234c8
-  asin: f0x234a4
-  atan: f0x2343c
-  atan2: f0x23460
-  ceil: f0x23418
-  cos: f0x233d0
-  cosh: f0x233f4
-  deg: f0x22e18
-  exp: f0x233ac
-  floor: f0x23030
-  fmod: f0x23368
-  frexp: f0x2332c
+__root__: &t0xfff91348
+ _VERSION: Lua 5.1
+ add_zeros: f0xfff9bdb8
+ assert: fbuiltin#2
+ collectgarbage: fbuiltin#27
+ copy: f0xfff9be70
+ dofile: fbuiltin#25
+ dump: f0xfff91308
+ error: fbuiltin#19
+ gcinfo: fbuiltin#26
+ getaddr: f0xfff9be58
+ getfenv: fbuiltin#10
+ getmetatable: fbuiltin#8
+ ipairs: fbuiltin#7
+ load: fbuiltin#23
+ loadfile: fbuiltin#22
+ loadstring: fbuiltin#24
+ mixed_sorter: f0xfff9bdd0
+ module: f0xfff93598
+ newproxy: fbuiltin#28
+ next: fbuiltin#4
+ opairs: f0xfff9be00
+ order_keys: f0xfff9bde8
+ pairs: fbuiltin#5
+ pcall: fbuiltin#20
+ print: fbuiltin#29
+ rawequal: fbuiltin#14
+ rawget: fbuiltin#12
+ rawset: fbuiltin#13
+ rawstr: f0xfff9be40
+ require: f0xfff935d8
+ select: fbuiltin#16
+ setfenv: fbuiltin#11
+ setmetatable: fbuiltin#9
+ strpad: f0xfff9bda0
+ tonumber: fbuiltin#17
+ tostring: fbuiltin#18
+ type: fbuiltin#3
+ unpack: fbuiltin#15
+ xpcall: fbuiltin#21
+ _G: *t0xfff91348
+ arg: &t0xfff93728
+  "-1": luajit
+  0: run.lua
+ bit: &t0xfff962c0
+  arshift: fbuiltin#68
+  band: fbuiltin#71
+  bnot: fbuiltin#64
+  bor: fbuiltin#72
+  bswap: fbuiltin#65
+  bxor: fbuiltin#73
+  lshift: fbuiltin#66
+  rol: fbuiltin#69
+  ror: fbuiltin#70
+  rshift: fbuiltin#67
+  tobit: fbuiltin#63
+  tohex: fbuiltin#74
+ coroutine: &t0xfff92f38
+  create: fbuiltin#32
+  resume: fbuiltin#34
+  running: fbuiltin#31
+  status: fbuiltin#30
+  wrap: fbuiltin#36
+  yield: fbuiltin#33
+ debug: &t0xfff95d78
+  debug: fbuiltin#140
+  getfenv: fbuiltin#129
+  gethook: fbuiltin#139
+  getinfo: fbuiltin#131
+  getlocal: fbuiltin#132
+  getmetatable: fbuiltin#127
+  getregistry: fbuiltin#126
+  getupvalue: fbuiltin#134
+  setfenv: fbuiltin#130
+  sethook: fbuiltin#138
+  setlocal: fbuiltin#133
+  setmetatable: fbuiltin#128
+  setupvalue: fbuiltin#135
+  traceback: fbuiltin#141
+  upvalueid: fbuiltin#136
+  upvaluejoin: fbuiltin#137
+ io: &t0xfff942b0
+  close: fbuiltin#107
+  flush: fbuiltin#110
+  input: fbuiltin#111
+  lines: fbuiltin#113
+  open: fbuiltin#104
+  output: fbuiltin#112
+  popen: fbuiltin#105
+  read: fbuiltin#108
+  stderr: file (0x611a2cf0)
+  stdin: file (0x611a2c10)
+  stdout: file (0x611a2c80)
+  tmpfile: fbuiltin#106
+  type: fbuiltin#114
+  write: fbuiltin#109
+ jit: &t0xfff967f0
+  arch: x86
+  attach: fbuiltin#146
+  flush: fbuiltin#144
+  off: fbuiltin#143
+  on: fbuiltin#142
+  os: POSIX
+  status: fbuiltin#145
+  version: LuaJIT 2.1.0-beta1
+  version_num: 20100
+  opt: &t0xfff96ba8
+   start: fbuiltin#158
+ math: &t0xfff95250
+  abs: fbuiltin#37
+  acos: fbuiltin#47
+  asin: fbuiltin#46
+  atan: fbuiltin#48
+  atan2: fbuiltin#55
+  ceil: fbuiltin#39
+  cos: fbuiltin#44
+  cosh: fbuiltin#50
+  deg: f0xfff95a48
+  exp: fbuiltin#42
+  floor: fbuiltin#38
+  fmod: fbuiltin#57
+  frexp: fbuiltin#52
   huge: inf
-  ldexp: f0x232ec
-  log: f0x2323c
-  log10: f0x232c8
-  max: f0x22fc4
-  min: f0x22f58
-  modf: f0x231f0
+  ldexp: fbuiltin#58
+  log: fbuiltin#54
+  log10: fbuiltin#41
+  max: fbuiltin#60
+  min: fbuiltin#59
+  mod: fbuiltin#57
+  modf: fbuiltin#53
   pi: 3.1415926535898
-  pow: f0x231ac
-  rad: f0x22de8
-  random: f0x23054
-  randomseed: f0x22f3c
-  sin: f0x22ef4
-  sinh: f0x22f18
-  sqrt: f0x22eb4
-  tan: f0x22e6c
-  tanh: f0x22e90
- os: &t0x70d90
-  clock: f0x237d8
-  date: f0x23ac0
-  difftime: f0x23758
-  execute: f0x23714
-  exit: f0x2369c
-  getenv: f0x23670
-  remove: f0x2363c
-  rename: f0x235ec
-  setlocale: f0x23580
-  time: f0x23930
-  tmpname: f0x23810
- package: &t0x6fe90
-  config: "\
-   /\
-   ;\
-   ?\
-   !\
-   -\
-   "
-  cpath: /usr/lib/lua/5.2/?.so;/usr/lib/lua/5.2/loadall.so;./?.so
-  loadlib: f0x27808
-  path: /usr/share/lua/5.2/?.lua;/usr/share/lua/5.2/?/init.lua;/usr/lib/lua/5.2/?.lua;/usr/lib/lua/5.2/?/init.lua;./?.lua
-  searchpath: f0x27ad4
-  seeall: f0x273e0
-  searchers: *t0x705b0
-  loaded: &t0x6f948
+  pow: fbuiltin#56
+  rad: f0xfff95ad8
+  random: fbuiltin#61
+  randomseed: fbuiltin#62
+  sin: fbuiltin#43
+  sinh: fbuiltin#49
+  sqrt: fbuiltin#40
+  tan: fbuiltin#45
+  tanh: fbuiltin#51
+ os: &t0xfff94770
+  clock: fbuiltin#121
+  date: fbuiltin#122
+  difftime: fbuiltin#124
+  execute: fbuiltin#115
+  exit: fbuiltin#120
+  getenv: fbuiltin#119
+  remove: fbuiltin#116
+  rename: fbuiltin#117
+  setlocale: fbuiltin#125
+  time: fbuiltin#123
+  tmpname: fbuiltin#118
+ package: &t0xfff93288
+  config: 
+   /
+   ;
+   ?
+   !
+   -
+  cpath: ./?.so;/usr/local/lib/lua/5.1/?.so;/usr/local/lib/lua/5.1/loadall.so
+  loadlib: f0xfff93318
+  path: ./?.lua;/usr/local/share/luajit-2.1.0-beta1/?.lua;/usr/local/share/lua/5.1/?.lua;/usr/local/share/lua/5.1/?/init.lua
+  searchpath: f0xfff93358
+  seeall: f0xfff93398
+  loaded: &t0xfff92480
    extra: true
-   _G: *t0x6f478
-   bit32: *t0x70190
-   coroutine: *t0x6f998
-   debug: *t0x717c8
-   io: *t0x70fe8
-   math: *t0x72a10
-   os: *t0x70d90
-   package: *t0x6fe90
-   string: *t0x70340
-   table: *t0x70b68
-   pt: &t0x78948
-    __call: f0x75128
-    inner: f0x76d00
-    outer: f0x74410
-    safekey: f0x77de8
-    safeval: f0x6f2d0
-    write: f0x6f360
-    __index: *t0x78948
-    __metatable: *t0x78948
-  loaders: &t0x705b0
-   1: f0x70620
-   2: f0x70648
-   3: f0x70670
-   4: f0x70698
-  preload: &t0x70720
- string: &t0x70340
-  byte: f0x25234
-  char: f0x24768
-  dump: f0x254d4
-  find: f0x25db4
-  format: f0x24890
-  gmatch: f0x2470c
-  gsub: f0x25dbc
-  len: f0x2433c
-  lower: f0x2436c
-  match: f0x25dac
-  rep: f0x2416c
-  reverse: f0x23fb8
-  sub: f0x2518c
-  upper: f0x23ed8
- t: &t0x74a30
+   _G: *t0xfff91348
+   bit: *t0xfff962c0
+   coroutine: *t0xfff92f38
+   debug: *t0xfff95d78
+   io: *t0xfff942b0
+   jit: *t0xfff967f0
+   "jit.opt": *t0xfff96ba8
+   math: *t0xfff95250
+   os: *t0xfff94770
+   package: *t0xfff93288
+   string: *t0xfff94be0
+   table: *t0xfff93638
+   pt: &t0xfff9be18
+    __call: f0xfff9be88
+    inner: f0xfff9bfb0
+    outer: f0xfff9bff0
+    safekey: f0xfff9beb8
+    safeval: f0xfff9bed0
+    write: f0xfff9bea0
+    __index: *t0xfff9be18
+    __metatable: *t0xfff9be18
+  loaders: &t0xfff933d8
+   1: f0xfff93428
+   2: f0xfff93448
+   3: f0xfff93468
+   4: f0xfff93488
+  preload: &t0xfff93700
+   ffi: f0xfff96c48
+   "jit.profile": f0xfff96af0
+   "jit.util": f0xfff96b30
+   "table.clear": f0xfff93e68
+   "table.new": f0xfff93e28
+ string: &t0xfff94be0
+  byte: fbuiltin#75
+  char: fbuiltin#76
+  dump: fbuiltin#82
+  find: fbuiltin#83
+  format: fbuiltin#88
+  gfind: fbuiltin#86
+  gmatch: fbuiltin#86
+  gsub: fbuiltin#87
+  len: f0xfff94e00
+  lower: fbuiltin#80
+  match: fbuiltin#84
+  rep: fbuiltin#78
+  reverse: fbuiltin#79
+  sub: fbuiltin#77
+  upper: fbuiltin#81
+ t: &t0xfff9a1c0
   C: hello
-  D: *t0x74a30
-  A: &t0x74b78
+  D: *t0xfff9a1c0
+  A: &t0xfff9a978
    a: beep
    b: boop
    c: burp
-   d: *t0x786c0
-  B: &t0x786c0
+   d: *t0xfff9a9a0
+  B: &t0xfff9a9a0
    a: nude
    b: dude
    c: lewd
-   d: *t0x74b78
- table: &t0x70b68
-  concat: f0x2691c
-  insert: f0x26688
-  maxn: f0x26818
-  pack: f0x26778
-  remove: f0x26498
-  sort: f0x26dec
-  unpack: f0x26598
+   d: *t0xfff9a978
+ table: &t0xfff93638
+  concat: fbuiltin#91
+  foreach: f0xfff93b70
+  foreachi: f0xfff93aa8
+  getn: f0xfff93c00
+  insert: fbuiltin#90
+  maxn: fbuiltin#89
+  remove: f0xfff93d90
+  sort: fbuiltin#92
diff --git a/pt.lua b/pt.lua
index f5116c4..5f16f1b 100755
--- a/pt.lua
+++ b/pt.lua
@@ -1,4 +1,4 @@
-require('extra')
+require 'extra'
 
 local pt = {}
 pt.__index = pt
@@ -19,14 +19,29 @@ function getaddr(t)
     return rawstr(t):sub(#type(t) + 3)
 end
 
-function pt.__call(pt, t, writer, seen)
+function copy(t)
+    -- shallow copy
+    if type(t) ~= 'table' then return end
+    local new = {}
+    for key, value in pairs(t) do
+        new[key] = value
+    end
+    return new
+end
+
+function pt.__call(pt, args)
     -- print a table as semi-valid YAML
     -- with references to prevent recursion/duplication
+    local t = args.table or args[1]
     local self = {}
     setmetatable(self, pt)
-    self.seen = seen or {}
+    self.seen = copy(args.seen) or {}
+    self.skipped = copy(args.skipped) or {}
+    self.seen_elsewhere = args.seen or {}
+    self.depth = args.depth or 16
+    self.writer = args.writer or io.write
+    self.skeleton = args.skeleton or false
     self.queued = {}
-    self.writer = writer or io.write
     self:inner('__root__', t, '')
     return self.seen
 end
@@ -53,22 +68,31 @@ function pt.safeval(v, indent)
         return s
     end
     s = s:find('[\r\n]') and ('\n'..s):gsub('[\r\n]', '\n'..indent..' ') or s
-    local safe = ('%q'):format(s)
-    return s == safe:sub(2, -2) and s or safe
+    --local safe = ('%q'):format(s)
+    --return s == safe:sub(2, -2) and s or safe
+    -- TODO: finish matching valid characters
+    return s:find('[^%w_()[]{}.]') and ('%q'):format(s) or s
 end
 
 function pt:inner(k, v, indent)
     if type(v) ~= 'table' then
+        if self.skeleton then return end
         self:write(indent, pt.safekey(k), ': ')
         self:write(pt.safeval(v, indent), '\n')
         return
     end
 
     local addr = getaddr(v)
-
     self:write(indent, pt.safekey(k))
+
+    if #indent > self.depth or self.skipped[addr] then
+        --self.skipped[addr] = true -- TODO: extra logics
+        self:write(': #t', addr, '\n')
+        return
+    end
+
     if self.seen[addr] or self.queued[addr] then
-        self:write(': *t', addr, '\n')
+        self:write(': *t', addr, self.seen_elsewhere[addr] and ' #\n' or '\n')
         return
     end
 
@@ -90,7 +114,7 @@ function pt:outer(t, indent)
     for k,v in opairs(t) do
         if type(v) == 'table' then
             local addr = getaddr(v)
-            if not self.queued[addr] and not self.seen[addr] then
+            if not self.queued[addr] and not self.seen[addr] and not self.skipped[addr] then
                 self.queued[addr] = true
                 ours[k] = v
             else
diff --git a/run.lua b/run.lua
index 5e9e49d..5468bcf 100755
--- a/run.lua
+++ b/run.lua
@@ -30,11 +30,11 @@ function dump(t, fn, seen)
     local writer = function(...)
         file:write(...)
     end
-    seen = pt(t, writer, seen)
+    seen = pt{t, writer=writer, seen=seen}
 
     file:close()
     return seen
 end
 
-pt(t)
+pt{t}
 dump(_G, '_G.yml')