title: Call a python function from jinja2
body: <p>I am using jinja2, and I want to call a python function as a helper, using a similar syntax as if I were calling a macro. jinja2 seems intent on preventing me from making a function call, and insists I repeat myself by copying the function into a template as a macro.    </p>
  
  <p>Is there any straightforward way to do this?  And, is there any way to import a whole set of python functions and have them accessible from jinja2, without going through a whole lot of rigamarole (such as writing an extension)?</p>