The function creates a new sequence containing the concatenation of any number of sequences. However, unlike **REVERSE** and **COPY-SEQ**, which simply return a sequence of the same type as their single argument, **CONCATENATE** must be told explicitly what kind of sequence to produce in case the arguments are of different types. Its first argument is a type descriptor, like the argument to **MAKE-ARRAY**. In this case, the type descriptors you’ll most likely use are the symbols **VECTOR**, **LIST**, or .9 For example: