all? → true or false
all? {|element| ... } → true or false
all?(obj) → true or false
没有 block 没有参数
[0, 1, :foo].all? # => true
[0, nil, 2].all? # => false
[].all? # => true
有 block 没有参数
[0, 1, 2].all? { |element| element < 3 } # => true
[0, 1, 2].all? { |element| element < 2 } # => false
有参数
['food', 'fool', 'foot'].all?(/foo/) # => true
['food', 'drink'].all?(/bar/) # => false
[].all?(/foo/) # => true
[0, 0, 0].all?(0) # => true
[0, 1, 2].all?(1) # => false
