What are idioms for taking a head or a tail of a vector, either up to an index, or from an index to the end? Also -- is it necessary to use length(v) to refer to the last element? E.g., Python has v[:3] # indices 0,1,2 v[3:] # indices 3,4,... v[-1] # the last element of v v[:-1] # all but last Cheers, Alexy