def categories=(categories)
      raise TypeException unless categories.is_a?(Array)
      categories.each { |item|
        raise TypeException unless Category.all.include?(item)
        raise DuplicateElementException if @categories.include?(item)
        @categories.push(item)
      }
    end
def categories=(categories)
      raise TypeException unless categories.is_a?(Array)
      categories.each { |item|
        raise TypeException unless Category.all.include?(item)
        raise DuplicateElementException if @categories.include?(item)
        @categories.push(item)
      }
    end
Set array of categories

 Params:
 +categories+:: array of StatModule::Category