What's Cooking In Ruby 2.7

Transcript

1. 8IBUT$PPLJOH*O
   3VCZ
   ෢ऀথل !LOV
   
   

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2. ࣗݾ঺հ
   w ෢ऀথل"LJOPSJ.VTIB
   w 5XJUUFSIUUQTUXJUUFSDPNLOV
   w (JU)VCIUUQTHJUIVCDPNLOV
   w גࣜձࣾϚνϚν
   w 3VCZίϛολʔ
   w 'SFF#4%ίϛολʔ
   w 5FBN/PLPHJSJ
   w )VHJOOڞಉ։ൃऀ
   

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3. ࣗݾ঺հ
   w ࢓ࣄʢൈਮʣ
   w γʔαʔϒϩά͓Αͼ0&.αʔϏε
   w ΠʔϓϥεެࣜΞϓϦͷόοΫΤϯυ
   w ૬੮԰ެࣜΞϓϦͷόοΫΤϯυ
   w ۙ͝ॴ4/4ϚνϚν
   

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4. ϚνϚν
   w גࣜձࣾϚνϚν
   w ໨ࠇ۠ɺֶܳେֶӺ͔Βెา෼
   w ձࣾ঺հIUUQCJUMZNBDIJNBDIJJOUSP
   w ʮͻΒ͔Εͨɺͭͳ͕Γͷ͋Δ஍ҬࣾձΛͭ͘Δʯ
   w ۙ͝ॴ4/4ˍ஍Ҭ৘ใϝσΟΞIUUQTNBDIJNBDIJDPN
   w ΤϯδχΞ࠾༻தʂIUUQTXXXXBOUFEMZDPNDPNQBOJFTNBDIJNBDIJJODQSPKFDUT
   w ϚνϚνΛࢧ͑Δٕज़$IUUQTUDP0.FIZ-:& 3BJMT 3FBDU 1PTUHSF42- ʜ
   
   w ٕज़ϒϩάIUUQTUFDINBDIJNBDIJDPN
   

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5. 3VCZͰͷ։ൃ׆ಈ
   w ϨϙδτϦ؅ཧऀ
   w ։ൃΠϯϑϥ੔උ
   w ඪ४ϥΠϒϥϦͷॆ࣮
   w %JHFTUͷ֦ுɺϋογϡΞϧΰϦζϜ௥Ճ
   w 4FUͷ࣮૷
   w CJHEFDJNBM TZTMPH JQBEES [MJCͳͲͷΠϯϙʔτࢧԉ΍อक
   w 4IFMMXPSETʹTIFMMFTDBQF TIFMMKPJOΛ࣮૷
   w 3VCZͷϦϦʔε
   

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6. 3VCZͰͷ։ൃ׆ಈ
   w ૊ࠐΫϥεͷ֦ு
   w "SSBZTMJDF
   w &OVNFSBUPSͷಋೖ &OVNFSBCMFͷ֦ு
   w FBDI@DPOT FBDI@TMJDF
   w FBDI@XJUI@PCKFDU
   

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7. 3VCZͰͷ։ൃ׆ಈ
   w ࠷ۙ͸ɺ݄࣍ͷ3VCZ։ൃऀձٞʹग़੮ͯ͠ɺओʹ3BJMT
   8FC։ൃऀͷ؍఺͔ΒΠϯϓοτͨ͠Γɺࣗ෼͕୲౰͢
   ΔϥΠϒϥϦΛ͍͡Δ׆ಈ͕ϝΠϯͰ͢ɻ
   

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8. 3VCZʹ޲͚ͯ
   w ·͕ͩग़͔ͯΒϲ݄͔͠ܦ͍ͬͯ·ͤΜ͕ɺ΍ʹ޲͚ͨػೳ։ൃ΍ٞ
   ࿦͸͍Ζ͍Ζਐߦ͍ͯ͠·͢ɻͦͷҰ୺Ͱ΋ɺָ͘͠͝঺հͰ͖ͨΒͱࢥ͍·͢ɻ
   w ͜͜Ͱ͝঺հ͢Δͷ͸͋͘·ͰዞҙతʹબΜͩྫʹա͗ͣɺ໢ཏੑ͸͋Γ·ͤΜɻ
   w ڵຯͷ͋Δํ͸/&84ϑΝΠϧɺ3VCZ։ൃऀձٞͷٞࣄ࿥ɺ3FENJOFͰͷν
   έοτϕʔεͷٞ࿦Λ௥͍͔͚·͠ΐ͏ɻ
   w ։ൃऀಉ࢜ͷٞ࿦͸ඇৗʹଟ૬తͰߴจ຺Ͱ͕͢ɺʮ͍ΖΜͳ͜ͱ͕͋ΔΜͩͳ͋ʯ
   ఔ౓ͷड͚औΓͰߏ͍·ͤΜɻ
   w ։ൃਞ΁ͷϑΟʔυόοΫ͸ɺ͍ΖΜͳνϟϯωϧΛ௨ͯ͡ؾܰʹͲ͏ͧʂ5XJUUFS
   ͰͭͿ΍͚ͩ͘Ͱ΋໨ʹೖΔ͔΋
   

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9. ͓͠ͳ͕͖
   w ೖͬͨ΋ͷ
   w ৽จ๏obj.:meth
   w ແϒϩοΫQSPDͷஈ֊తഇࢭ
   w &OVNFSBCMFUBMMZ
   w ٫Լ͞Εͨ΋ͷ
   w ։ൃதɾݕ౼தͷػೳ
   w ࠓޙͷ3VCZͷ༧ఆ
   

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10. obj.:meth
    w obj.method(:meth)ͷ୹ॖจ๏
    w ϝιουΦϒδΣΫτΛऔΓग़͢
    w ैདྷͷ0CKFDUNFUIPE͸ϝιουݺͼग़ͩͬͨ͠
    w ϝιουΛऔΔͨΊʹϝιουΛݺͿඞཁ͕͋Δʜ

    ͍͔ʹ΋3VCZΒ͍͚͠Ͳʜ
    w ΦʔόʔϥΠυ͞Ε͍ͯΔ͔΋͠Εͳ͍

    ʢྫ3FRVFTUΦϒδΣΫτ)551ϝιουΛฦ͢ʣ
    w 0CKFDUͰͳ͘#BTJD0CKFDUΛܧঝͨ͠ΦϒδΣΫτʹ͸NFUIPEϝιο
    υ͕ͳ͍
    

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11. obj.:meth
    w ೚ҙͷΦϒδΣΫτʹରͯ͠ϝιουΛऔΓग़͍ͨ͠ͱ͖͸ɺΫϥε
    ͔ΒϝιουΛऔΓग़ͯ͠CJOEDBMM͢Δͱ͍͏ᷖԕͳखஈΛऔΔ
    ඞཁ͕͋ͬͨ
    • Object.instance_method(:method)

    .bind(obj)

    .call
    • ΦϒδΣΫτͷૉੑΛ໰ΘͣɺϝιουΛऔΓग़͢୹͍ه๏͕΄͍͠
    • ͍͔ͭ͘Ҋ͕͕͋ͬͨɺطଘจ๏ͱͷিಥ͕ͳ͘ɺγϯϘϧه๏
    ͔ΒϝιουΛ࿈૝͠΍͍͢ʮobj.:methʯʹܾఆ
    

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12. obj.:meth
    w ͨͱ͑͹ɺ͜͏͍͏ίʔυ͕୹͘ॻ͚ΔΑ͏ʹ
    w lines.map { |line| JSON.parse(line) }

    ↓

    lines.map(&JSON.:parse)
    • ͨͩ͠ɺself͸লུͰ͖ͳ͍͜ͱͱͨ͠
    w lines.each { |line| puts line }

    ↓

    lines.each(&self.:puts)
    w obj.each(&.:meth)Λڐͯ͠͠·͏ͱɺobj.each(&:meth)ͱݟͨ໨͕
    ӝೋͭͳͷʹશવҧ͏ҙຯʹͳΔͷͰ໨ʹ༏͘͠ͳ͍ɺͱ͍͏.BU[ͷࢦఠʹ
    ΑΔ
    

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13. ແϒϩοΫQSPDͷஈ֊తഇࢭ
    w ϝιουఆٛதͰϒϩοΫͳ͠ͷQSPDʹΑͬͯϝιουʹ౉͖ͬͯͨϒϩοΫΛ
    औಘ͢Δ͜ͱ͕Ͱ͖Δ
    • def each_key

    keys.each(&proc)

    end
    • proc͸Proc.newͱॻ͍ͯ΋ಉ͡ɺଞʹlambda΋͋Δ
    • block_given?ͰϒϩοΫ͕౉͞Ε͔ͨͲ͏͔Λ൑ఆͰ͖ɺyieldͰݺͼग़ͤ
    Δͷͱ߹Θͤͯɺ໌ࣔతʹҾ਺Λॻ͔ͳͯ͘΋౉͞ΕͨϒϩοΫΛར༻Ͱ͖ͨ
    w ͜ͷػೳΛഇࢭ͠Α͏ͱ͍͏ํ޲ʹͳͬͨ
    w ແϒϩοΫprocͱProc.new͸͔ΒܯࠂɺແϒϩοΫlambda͸ഇࢭ
    

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14. ແϒϩοΫQSPDͷஈ֊తഇࢭ
    w എܠͱͯ͠͸ɺ࠷దԽ΍ޡΓݕग़ͷͨΊɺ͋Δϝιου͕
    ϒϩοΫΛऔΔͷ͔Ͳ͏͔Λ੩తʹ൑ఆ͍ͨ͠ɺཧ૝తʹ
    ͸Ҿ਺ϦετͰ໌͍ࣔͤͨ͞ɺͱ͍͏ಈػ͕͋Δ
    w ϒϩοΫΛऔΒͳ͍ϝιουʹϒϩοΫΛ౉ͯ͠΋ɺϝ
    ιουଆͰνΣοΫ͠ͳ͍ݶΓΤϥʔ΍ܯࠂʹ͸ͳΒ
    ͳ͍
    w ࢖ΘΕΔͱࢥͬͯϒϩοΫΛ౉͕࣮ͨ͠͸࢖ΘΕͣແ
    ҙຯͱ͍͏ޡΓʹؾ͚ͮͳ͍ɺͱ͍͏໰୊
    

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15. ແϒϩοΫQSPDͷஈ֊తഇࢭ
    w ͨͩɺ$3VCZʹ͸௕͍ؒɺdef method(&block)ͱϒϩοΫΛҾ਺Ͱ
    ड͚औΔͷ͸஗͍ͱ͍͏໰୊͕͋Γɺख़࿅޻͸ॻ͍ͯ͘Εͳ͔ͬͨ
    w yield͸ɺ౉͞ΕͨϒϩοΫΛ௚઀ݺͿ໋ྩʹίϯύΠϧ͞ΕΔ
    w ҰํɺԾҾ਺Ϧετʹ&blockͱॻ͘ͱɺϒϩοΫ͔Β1SPDΦϒδΣΫ
    τΛੜ੒্ͨ͠ͰɺϩʔΧϧม਺ʹ୅ೖ͞ΕΔ
    w ͞Βʹblock.callͱ͢ΔͱϩʔΧϧม਺Λࢀর͠ɺ1SPDΦϒδΣΫ
    τʹରͯ͠ϝιου͕ݺͼग़͞ΕΔ
    w Կεςοϓ΋ଟ͍ʜ
    

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16. ແϒϩοΫQSPDͷஈ֊తഇࢭ
    w 3VCZͰɺԾҾ਺Ϧετʹ&blockͱॻ͍ͯ΋ɺ࣮ࡍʹblockΛ࢖͏
    ·Ͱ1SPDΦϒδΣΫτͷੜ੒Λ஗Ԇ͢ΔΑ͏ʹͳͬͨ
    w தͰblock_given?ͱyieldΛ࢖ͬͨ··ɺϒϩοΫΛऔΔ͜ͱΛԾ
    Ҿ਺ϦετͰදݱͯ͠΋ੑೳ্ͷϖφϧςΟ͕ͳ͘ͳͬͨ
    w 3VCZͰɺblock.call͸yieldͱಉ౳ͷੑೳʹͳͬͨ
    w ͨͩɺcallͷΦʔόʔϥΠυ༗ແΛ֬ೝ͢ΔͳͲ໘౗ͳ࣮૷ͷࣀ෺
    w ͜ΕͰɺ໌ࣔతʹ&blockͱblock.callΛ࢖͏ελΠϧΛਪ঑Ͱ͖ΔΑ
    ͏ʹͳͬͨ
    

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17. ແϒϩοΫQSPDͷஈ֊తഇࢭ
    w ٯʹɺʮϒϩοΫΛऔΒͳ͍͜ͱʯΛ໌ࣔͰ͖ΔΑ͏ʹ͢΂͖͔ɺͱ͍
    ͏ٞ࿦΋ਐΜͰ͍Δ
    w ౰ॳ͸ɺdef foo(&nil)ͱॻ͘͜ͱʹ͢Ε͹͍͍ͷͰ͸ɺͱ·ͱ
    ·Γ͔͚ͨ
    w ͔͠͠ɺͦ͏͢ΔͱʮϒϩοΫΛऔΒͳ͍ϝιου͢΂ͯʹ&nilΛ
    ೖΕΑ͏ʯͱ͍͏େྔͷ13͕Ұؾʹԡ͠دͤΔةዧ͕͋ΔͷͰऔ
    Γ΍Ίʹ
    w ݱࡏ͸ɺίϯύΠϧ࣌ͷ੩తղੳͰͰ͖ͳ͍͔ɺͱ͍͏औΓ૊Έ͕ࢼ͞
    Ε͍ͯΔ
    

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18. ແϒϩοΫQSPDͷஈ֊తഇࢭ
    w ͨͩɺTVQFSͱ͍͏น͕ൃݟ͞ΕΔ
    w super͋Δ͍͸super()ͱॻ͘ͱɺԿ΋ࢦఆ͍ͯ͠ͳ͍͕ɺ
    ౉͖ͬͯͨϒϩοΫΛεʔύʔϝιουʹ౉͢Α͏ʹͳ͍ͬͯΔ
    w superͷํ͸෼͔Δ͕ɺsuper()ͷํ͸Ұମͳͥʜ
    w ͦͷͨΊɺεʔύʔϝιου΋ḷͬͯݟͳ͍ͱϒϩοΫҾ਺Λ࢖ͬ
    ͍ͯΔͷ͔͸Θ͔Βͳ͍
    w ݱࡏ΋طଘͷϢʔβίʔυΛؚΊௐࠪɾݚڀ͕ਐߦத$
    

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19. &OVNFSBCMFUBMMZ
    w ཁૉΛ஋ผʹ਺͑Δϝιου
    • ["a", "b", "b", "c", "a", "a"].tally

    # => { "a" => 3, "b" => 2, "c" => 1 }
    • SQLͷGROUP BY+COUNT()ͷΑ͏ͳ΋ͷ
    • ࠓ·Ͱ͸group_byΛ࢖ͬͯ͜Μͳ෩ʹͤ͟ΔΛಘͳ͔ͬͨॲཧ
    • ["a", "b", "b", "c", "a", "a"]

    .group_by(&:itself)

    .transform_values(&:size)
    

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20. &OVNFSBCMFUBMMZ
    w ౰ॳ͸count_byͱ͍͏໊લͰɺϒϩοΫΛऔΔܗͰఏҊ͞Ε͍ͯͨʢϒϩοΫΛద
    ༻ͨ͠஋Ͱूܭ͢Δʣ
    w ͔͠͠ɺ͍͔ͭ͘ͷ೉఺ͰࢍಉΛಘΒΕͣ
    w ໊લ͕͍·͍ͪcountͱͷରশੑ͕ͳ͍ʢsort_bysort max_bymaxͳ
    Ͳ͔Βͷྨਪ͕ޮ͔ͳ͍ʣ
    w ػೳ͕ଟ͍ϒϩοΫΛऔΔͷ͸ΦϓγϣφϧͰ͸ʁඞཁͳΒmap͔ͯ͠Β౉
    ͤ͹͍͍
    w γϡϫϧπม׵͍ͨ͜͠ͱ΋͋Δ͔΋͠Εͳ͍͕ɺ୅ද஋ΛͲ͏͢Δ͔࢓
    ༷ΛܾΊ೉͍
    w tallyͱ͍͏໊લΛಘͯɺϒϩοΫΛऔΒͳ͍γϯϓϧͳܗͰ࠾༻
    

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21. &OVNFSBCMFUBMMZ
    w UBMMZͱ͸਺Λ਺͑ͯه࿥͢Δ͜ͱͰɺࢴ΍ࠇ൘ʹҰຊͣͭઢΛॻ
    ͖ͳ͕ΒΧ΢ϯτ͢ΔͨΊͷه߸ͷݺশͰ΋͋Δʢ೔ຊͰͷʮਖ਼ʯ
    ʹ͋ͨΔه߸ɺʮ㠟ʯͷΑ͏ͳܗʣ
    w ͪͳΈʹ6OJDPEFͰʮਖ਼ʯͱͱ΋ʹೖΓ·ͨ͠

    IUUQTUXJUUFSDPNLFO@MVOEFTUBUVT
    
    

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22. ٫Լ͞Εͨ΋ͷ
    w BVUPMPBEͷഇࢭ⚡
    w .BU[͸εϨουηʔϑςΟͷ؍఺͔Βຊ࣭తʹةͳ͍ͷͰͣͬͱফͨ͠
    ͍೿
    w 3BJMT͕DPOTU@NJTTJOHͰͷࣗಈϩʔυػߏΛ΍ΊͯBVUPMPBEΛ࢖͏
    ;FJUXFSLΛͰ࠾༻ɺͱ͍͏͜ͷλΠϛϯάͰ͸͠͝Λ֎͢ͷ͔⽐ͱ
    ࢲͷதͰ૽વ
    w ͔͠͠3BJMTΞϓϦͷ։ൃͰ͸FBHFSMPBEJOHͩͱϓϩηεىಈɾ࠶ىಈ
    ͕ॏ͗͢ΔͷͰ͜͏͍͏ػߏ͸ඞਢͱઆಘ☝
    w গͳ͘ͱ΋3VCZYͷؒ͸࢒͢ɺͱ͍͏.BU[ͷݴ࣭Λಘͨ
    

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23. ٫Լ͞Εͨ΋ͷ
    w BVUPMPBEͷഇࢭ
    w ͦͷޙɺBVUPMPBEΛΑΓ҆શʹ͢ΔͨΊͷݚڀͱվम͕ਐΜͰ
    ͍Δ
    w IUUQXXXBLSPSHEIUNMB@@
    w IUUQXXXBLSPSHEIUNMB@@@
    w IUUQTCVHTSVCZMBOHPSHJTTVFT
    w IUUQTCVHTSVCZMBOHPSHJTTVFT
    

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24. ٫Լ͞Εͨ΋ͷ
    w "SSBZ΍)BTI΋ɺ4USJOHͷΑ͏ʹσϑΥϧτͰϑϦʔζ͢ΔϞʔυ͕΄͠
    ͍ɺ͋Δ͍͸୯߲ͰEVQGSFF[F͍ͨ͠
    w IUUQTCVHTSVCZMBOHPSHJTTVFT
    w ʮͦΜͳʹ΄͍͠ʁʯ·ͩջٙత
    w Ͱ΋3VCPDPQར༻ऀ͔Β͢Δͱɺఆ਺഑ྻɾϋογϡʹ.freezeΛ෇
    ͚ͯճΒΕΔܦݧ͸ۤʑ͍͠ʜ
    w ͍ͣΕ·ͨνϟϯε͋Δ͔΋
    

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25. ։ൃதɾݕ౼தͷػೳ
    w #FHJOMFTT 4UBSUMFTT
    3BOHFT
    w IUUQTCVHTSVCZMBOHPSHJTTVFT
    w &OEMFTT3BOHFT @ary[1..]
    ͕ೖͬͨͷͰɺࠓ౓͸ࠨ୺ଆΛলུͨ͠΋ͷ΋
    ೖΕ͍ͨ
    w "DUJWF3FDPSEͳͲͷ%4-ͰศརProduct.where(price: ..1000)
    w &OEMFTT3BOHFT΋ಋೖޙʹ͍͔ͭ͘໰୊͕ൃݟɾରॲ͞ΕͨͷͰɺͦΕΒͷ
    ख౰͕ͯऴΘͬͯམͪண͍͔ͯΒ
    w &OVNFSBUPS:JFMEFSUP@QSPD
    w IUUQTCVHTSVCZMBOHPSHJTTVFT
    

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26. ։ൃதɾݕ౼தͷػೳ
    w σϑΥϧτϒϩοΫҾ਺@1 @2 ʜ
    w IUUQTCVHTSVCZMBOHPSHJTTVFT
    w ͣͬͱ๬·Ε͍ͯΔػೳnumbers.map { "%02x" % @1 }
    w طଘจ๏ͱিಥͷͳ͍ح੻ͷҊʢ@1 @2,…ʣʹظ଴
    w ύλʔϯϚονػೳʢDBTFJOߏจʣ
    w IUUQTCVHTSVCZMBOHPSHJTTVFT
    w ڧ͘଴ͪ๬·Ε͖ͯͨػೳ
    w εΫϦϓτݴޠͷதͰ͸ڧྗͰ3VCZͷڧΈͱݴΘΕ͖͕ͯͨɺؔ਺ܕݴޠ͕ϝδϟʔ
    ʹͳ͖ͬͯͨࠓͰ͸ͪΐͬͱݟྼΓ͢Δ
    

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27. ։ൃதɾݕ౼தͷػೳ
    w &4ελΠϧͷϋογϡ؆ศه๏ʢpFMEQVOOJOHʣ
    w IUUQTCVHTSVCZMBOHPSHJTTVFT
    w {

    name: name,

    type: type,

    created_at: created_at

    }

    ↓

    { name, type, created_at }

    

    ͳͲͱॻ͖͍ͨͳɺͱ͍͏ྫͷ΍ͭ
    w .+*5ʹΑΔ͞ΒͳΔߴ଎Խ
    

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28. ࠓޙͷ3VCZͷ༧ఆ
    w ೥݄
    w ೔ʹ։ൃऀձٞIUUQTCVHTSVCZMBOHPSHJTTVFT
    w 6OJDPEF͕ग़ͨΒɺ3VCZYΛϦϦʔε
    w ೥݄
    w 3VCZ,BJHJձظલ೔ʹ։ൃऀձٞ
    w ৽ݩ߸͕ൃද͞ΕͨΒ6OJDPEF͕ग़Δ
    w ͦΕΛ଴ͬͯ3VCZZΛϦϦʔε
    w ຖ݄։ൃऀձٞ
    w νϟϯε͸ຖ݄ IUUQTCVHTSVCZMBOHPSHJTTVFT
    w ೥݄
    w ೔3VCZϦϦʔε
    

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