How to generate HMAC in Authorization header

[swabha]

Hi
I am having a ball with pyresttest and it pummels Java to the ground! Great work guys! My YAMLs were working just fine until the dev team introduced HMAC into the midst. So now I need to generate HMAC as part of an "X-signature:" header when sending out the request which is essentially a function call taking in parameters like current date and the POST bytes of the request-->
hmac.new(, <post_data>, , hashlib.sha256).hexdigest()

How do I make this function call from my YAML?