There are some algorithms which use other algorithms in their 'inner-loop'. If possible, we try to implement these types of algorithms on top on the existing python wrappers. If we can fully implement the algorithm in this way, without having to call an external application, we term this a Meta-Wrapper, since it implements a meta-algorithm (an algorithm over an algorithm).
The advantage to implementing in this way, is that a meta-wrapper can be used in conjunction with any other instance of a ML_Algorithm, including itself or other meta-wrapper. This lends enormous power to the family of ML_Algorithms when taken as a whole.