The <append> block allows you to add an element to the end of a list; it directly references the Python function: .append()
See the Python documentation for more details.
•« list » : the variable to which you want to add an element; the default value is an empty list.
•« elem » : the element to be added (at the end) to the “list” input; the default value is 0 (int)
•« list » : the list containing the new element (of the type defined by the “type” input)
The “list” input and output are of type list; the “elem” input can be of any type
Since “list” output = “list” input.append(“elem”), after the block executes, the two lists are identical