def any? axis=:vector, &block
      if %i[vector column].include?(axis)
        @data.any?(&block)
      elsif axis == :row
        each_row do |row|
          return true if yield(row)
        end
        false
      else
        raise ArgumentError, "Unidentified axis #{axis}"
      end
    end
Works like Array#any?.

@param [Symbol] axis (:vector) The axis to iterate over. Can be :vector or
:row. A Daru::Vector object is yielded in the block.
@example Using any?
df = Daru::DataFrame.new({a: [1,2,3,4,5], b: ['a', 'b', 'c', 'd', 'e']})
df.any?(:row) do |row|
row[:a] < 3 and row[:b] == 'b'
end #=> true