'Get a list of unique basic fused types, from a list of
(possibly) compound fused types.'

def _get_fused_base_types(self, fused_compound_types):

    base_types = []
    seen = set()
    for fused_type in fused_compound_types:
        fused_type.get_fused_types(result=base_types, seen=seen)
    return base_types
