　晋太元中，武陵人捕鱼为业。缘溪行，忘路之远近。忽逢桃花林，夹岸数百步，中无杂树，芳草鲜美，落英缤纷。渔人甚异之，复前行，欲穷其林。　　林尽水源，便得一山，山有小口，仿佛若有光。便舍船，从口入。初极狭，才通人。复行数十步，豁然开朗。土地平旷，屋舍俨然，有良田、美池、桑竹之属。阡陌交通，鸡犬相闻。其中往来种作，男女衣着，悉如外人。黄发垂髫，并怡然自乐。　　见渔人，乃大惊，问所从来。具答之。便要还家，设酒杀鸡作食。村中闻有此人，咸来问讯。自云先世避秦时乱，率妻子邑人来此绝境，不复出焉，遂与外人间隔。问今是何世，乃不知有汉，无论魏晋。此人一一为具言所闻，皆叹惋。余人各复延至其家，皆出酒食。停数日，辞去。此中人语云：“不足为外人道也。”(间隔一作：隔绝) 　　既出，得其船，便扶向路，处处志之。及郡下，诣太守，说如此。太守即遣人随其往，寻向所志，遂迷，不复得路。　　南阳刘子骥，高尚士也，闻之，欣然规往。未果，寻病终。后遂无问津者。 sh-3ll

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DIR:/opt/alt/ruby18/share/ri/1.8/system/Array/

Current File : //opt/alt/ruby18/share/ri/1.8/system/Array/combination-i.yaml

--- !ruby/object:RI::MethodDescription 
aliases: []

block_params: 
comment: 
- !ruby/struct:SM::Flow::P 
  body: When invoked with a block, yields all combinations of length <em>n</em> of elements from <em>ary</em> and then returns <em>ary</em> itself. The implementation makes no guarantees about the order in which the combinations are yielded.
- !ruby/struct:SM::Flow::P 
  body: When invoked without a block, returns an enumerator object instead.
- !ruby/struct:SM::Flow::P 
  body: "Examples:"
- !ruby/struct:SM::Flow::VERB 
  body: "    a = [1, 2, 3, 4]\n    a.combination(1).to_a  #=&gt; [[1],[2],[3],[4]]\n    a.combination(2).to_a  #=&gt; [[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]]\n    a.combination(3).to_a  #=&gt; [[1,2,3],[1,2,4],[1,3,4],[2,3,4]]\n    a.combination(4).to_a  #=&gt; [[1,2,3,4]]\n    a.combination(0).to_a  #=&gt; [[]] # one combination of length 0\n    a.combination(5).to_a  #=&gt; []   # no combinations of length 5\n"
full_name: Array#combination
is_singleton: false
name: combination
params: |
  ary.combination(n) { |c| block }    -> ary
  ary.combination(n)                  -> enumerator

visibility: public