Iterates over layout objects pointed in `self.slice` executing `function` on them
        It passes `function` last layout object

def map(self, function):
        """
        Iterates over layout objects pointed in `self.slice` executing `function` on them
        It passes `function` last layout object
        """
        if isinstance(self.slice, slice):
            for i in range(*self.slice.indices(len(self.layout.fields))):
                function(self.layout.fields[i])

        elif isinstance(self.slice, list):
            # A list of pointers  Ex: [[[0, 0], 'div'], [[0, 2, 3], 'field_name']]
            for pointer in self.slice:
                position = pointer[0]

                layout_object = self.layout.fields[position[0]]
                for i in position[1:]:
                    previous_layout_object = layout_object
                    layout_object = layout_object.fields[i]

                # If update_attrs is applied to a string, we call to its wrapping layout object
                if (
                    function.__name__ == 'update_attrs'
                    and isinstance(layout_object, string_types)
                ):
                    function(previous_layout_object)
                else:
                    function(layout_object)