This module implements the Levenshtein edit distance. The Levenshtein edit
distance is a measure of the degree of proximity between two strings. This
distance is the number of substitutions, deletions or insertions ("edits")
needed to transform one string into the other one (and vice versa). When
two strings have distance 0, they are the same. To learn more about the
Levenshtein metric, have a look at the wikipedia page
<http://en.wikipedia.org/wiki/Levenshtein_distance>.
