def METHOD_NAME(type_):
    if isinstance(type_, ARRAY):
        if isinstance(type_.item_type, sa.Integer):
            return [0]
        elif isinstance(type_.item_type, sa.String):
            return ['a']
        elif isinstance(type_.item_type, sa.Numeric):
            return [Decimal('0')]
        else:
            raise TypeError('Unknown array item type')
    else:
        return 'a'