8 lines
		
	
	
		
			160 B
		
	
	
	
		
			Ruby
		
	
	
	
	
	
			
		
		
	
	
			8 lines
		
	
	
		
			160 B
		
	
	
	
		
			Ruby
		
	
	
	
	
	
| module Enumerable
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|   def group_by
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|     inject({}) do |h, e|
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|       h.fetch(yield(e)) { |k| h[k] = [] } << e; h
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|     end
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|   end unless method_defined?(:group_by)
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| end
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