Net/ssh in ruby. ssh.exec fails

I just finished install net-ssh-2.1.0.gem.
And following v2 example, I did this:

irb(main):005:0> Net::SSH.start(“sh-ubuntu6”, “vdeadmin”, “fishbowl”) do
irb(main):006:1* puts ssh.exec(“pwd”)
irb(main):007:1> end
NoMethodError: private method `exec’ called for

undefined method `exec!’
exec - private method.

any one has encountered this before?

I googled online, search in mailer archive, and tried with several
different versions of net/ssh.

none of them helps.