(&:odd?)について

 > a, = (1..5).partition(&:odd?)
 => [[1, 3, 5], [2, 4]] 
 > a = (1..5).partition(&:odd?)
 => [[1, 3, 5], [2, 4]] 
 > a, b = (1..5).partition(&:odd?)                                                                            
 => [[1, 3, 5], [2, 4]] 
 > b
 => [2, 4] 

 > a, = (1..5).partition(&:odd?)

↑なぜaの後ろに「,」が入っていたのか不思議だったが下記のコードで納得

 > a, b = (1..5).partition(&:odd?)                                                                            
 => [[1, 3, 5], [2, 4]] 
 > b
 => [2, 4] 

a, = (1..5).partition { |num|  num.odd? }