'Add a deployment to this chain.
:type add: Single :class:`Deployment` or a ``list`` of
:class:`Deployment`
:keyword add: Adds this deployment to the others already in this
object.'

def add(self, add):

    if (add is not None):
        add = (add if isinstance(add, (list, tuple)) else [add])
        self.steps.extend(add)
