Class EmployeeDataBase Object employees
Methods EmployeeDataBase 
   new
      employees <- Dictionary new.
      ^self
|
   add: anEmployee
      (anEmployee isKindOf: Employee)
           ifTrue: [
            employees
               at: (anEmployee empNum)
               put: anEmployee.
            ^self
         ]
         ifFalse: [
            smalltalk error: 'You can only add employees!'
         ]
|
   do: aBlock
      employees do: aBlock.
|
   findSkill: aSkill
      | empsWithSkill |
      empsWithSkill <- Set new.
      employees do: [
          :emp |
          (emp hasSkill: aSkill)
             ifTrue: [empsWithSkill add: emp]].
      ^empsWithSkill.
]