The IsEodermdrome command checks whether a string s is an eodermdrome, returning true if it is, and false otherwise.

An eodermdrome is a string with the property that the sequence of consecutive digrams of the string form an Eulerian trail in the complete graph on the characters appearing in the string.

All of the StringTools package commands treat strings as (null-terminated) sequences of $8$-bit (ASCII) characters.  Thus, there is no support for multibyte character encodings, such as unicode encodings.

$\mathrm{with}\left(\mathrm{StringTools}\right)\:$

$\mathrm{IsEodermdrome}\left(''EODERMDROME''\right)$

$\mathrm{true}$

$\mathrm{IsEodermdrome}\left(''SURTOUTSORS''\right)$

$\mathrm{true}$

$\mathrm{IsEodermdrome}\left(''STRING''\right)$

$\mathrm{false}$

http://www.oulipo.net/contraintes/docs/eodermdrome