In this example, we demonstrate how to obtain string features
by using a sliding window in a memory-efficient way. Instead of copying
the string for each position of the sliding window, we only store a reference
with respect to the complete string. This is particularly useful, when working
with genomic data, where storing all explicitly copied strings in memory
quickly becomes infeasible. In addition to a sliding window (of a particular
length) over all position, we also support defining a custom position
list.
