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Haven't seen one personally. But I can related exactly due to that.

One of my friends once found an old Kundalini yoga guru in India.
And what happened?
In typical old school fashion the guy refused to teach him and said:
"You live in n ashram and if I teach you, you will try to teach others and that is not good."

That is quite Wise honestly, I respect that decision. Its not because hes afraid that the information will be leaked out, but rather thought at a wrong way.