This is a really fun piece, written by a colleague of mine, Mike England as part of an educational series on how to improvise. The arrangement of this piece doesn't actually contain any improvised sections, but there is a written out solo for the vibraphone, which could be interpretted in lots of ways. 
Mocha starts off as a funk piece, then moves to a Latin songo, where the vibraphone commences its solo. The piece then returns to the funky groove to close out the piece.