'Initialize transformer with configured parameters.
:param source: dict containing source sample unit
:param target: dict containing target sample name, type,
unit and scaling factor (a missing value
connotes no change)'

def __init__(self, source=None, target=None, **kwargs):

    self.source = (source or {})
    self.target = (target or {})
    super(BaseConversionTransformer, self).__init__(**kwargs)
