Detect the data modality based on the resource_types.

        resource_types == ['table'] => 'single_table'
        resource_types == ['something_else'...] => 'something_else'   # this is not likely
        resource_types == ['table', 'table'...] => 'multi_table'
        resource_types == ['table', 'something_else'...] => 'something_else'

def get_data_modality(self):
        """Detect the data modality based on the resource_types.

        resource_types == ['table'] => 'single_table'
        resource_types == ['something_else'...] => 'something_else'   # this is not likely
        resource_types == ['table', 'table'...] => 'multi_table'
        resource_types == ['table', 'something_else'...] => 'something_else'
        """
        resource_types = self.get_resource_types()
        first_type = resource_types[0]
        if first_type != 'table':
            return first_type

        elif len(resource_types) == 1:
            return 'single_table'

        else:
            second_type = resource_types[1]
            if second_type == 'table':
                return 'multi_table'

            return second_type