new style
Start '{% with what_am_i=simple.name %}I'm {{what_am_i}}{% endwith %}' End
Start '{% with what_am_i=simple.name %}I'm {{what_am_i}}11{% endwith %}' End
Start '{% with number=7, what_am_i="guest" %}I'm {{what_am_i}}{{number}}{% endwith %}' End

more with tests
{% with first_comment=complex.comments|first %}{{ first_comment.Author }}{% endwith %}
{% with first_comment=complex.comments|first %}{{ first_comment.Author.Name }}{% endwith %}
{% with first_comment=complex.comments|last %}{{ first_comment.Author.Name }}{% endwith %}