===== collection =====
 one -to- many relationship => use a collection

==== OrderedCollection ====
 dynamincally sized collection

 ex
<code>
 | oc |
 oc := OrderedCollection new: 1.
 1 to: 3 do: [:n | a add: n].
 ^ a

 an OrderedCollection(1 2 3)
</code>
==== RunArry ====
 How do you compactly code (OredredCollection or Array)
 예
<code>
 #(plain plain plain bold bold bold bold) -대체-> 3--#plain, 4--#bold
</code>

==== Set ====
  don't want duplicates in collection
 예
{{{ 
 #(1 1 1 1 2 2 2) asSet. 

 a Set(1 2)
</code>

==== Equality Method ====
 새로운 object를 추가할때 equaluty 유지하기?

==== Hashing Method ====

==== Dictionary ====
 

==== Sorted Collection ====
 collection 에서 어떤 특정 조건의 sorting 

==== Array ====
 colletion with fixed number of element
 예
<code>
 | a | 
 a := Array new: 5. 
 1 to: a size do: [ :n | a at: n put: n ]. 
 ^ a
 
 #(1 2 3 4 5)
</code>

==== ByteArray ====
 homogenous(균일한) information을 저장할때 사용

==== Interval ====
<code>
 sequence number in collection
 (1 to: 20) do: [:each | ...]
</code>
 예
<code>
 | collection oc | 
 collection := 1 to: 20 by: 2. 
 oc := OrderedCollection new. 
 oc addAll: collection. 
 ^ oc 
 
 an OrderedCollection(1 3 5 7 9 11 13 15 17 19)
</code>