Hi, in IDL/GDL, if at have an array x = [1,2,3] ?I can simply construct a new array by y = [0,x] which would give [0,1,2,3] I know you can do this case with x[0:0] = [0] but obviously more complicated cases are conceivable, common for me, in fact x=[1,2,3] y=[5,6,7] z=[0,x,4,y,8] result [0,1,2,3,4,5,6,7,8] or maybe even z=[0,x[0:2],5] and so forth. On the other hand, if you have a function you can pass the list of arguments to another function def f(*args): ? g(*args) which expands the list args. ?So, would it be possible - not even reasonable to have something similar for list and arrays, maybe dictionaries, in comprehensions as well? x = [1,2,3] y = [0,*x] to obtain [0,1,2,3] or similar for lists x = (1,2,3) y = (0,*x) to obtain (0,1,2,3) (for dictionaries, which are not sorted, the extend function seems fine) Or is there a way of doing this that in a similarly compact and obvious way I did not yet discover? -Alexander