Make a copy of {expr}. For Numbers and Strings this isn't different from using {expr} directly. When {expr} is a |List| a full copy is created. This means that the original |List| can be changed without changing the copy, and vice versa. When an item is a |List| or |Dictionary|, a copy for it is made, recursively. Thus changing an item in the copy does not change the contents of the original |List|. A |Dictionary| is copied in a similar way as a |List|. When {noref} is omitted or zero a contained |List| or |Dictionary| is only copied once. All references point to this single copy. With {noref} set to 1 every occurrence of a |List| or |Dictionary| results in a new copy. This also means that a cyclic reference causes deepcopy() to fail. Nesting is possible up to 100 levels. When there is an item that refers back to a higher level making a deep copy with {noref} set to 1 will fail. Also see |copy()|. Can also be used as a |method|: GetObject()->deepcopy()