starts-with-subseq (prefix sequence &rest args &key return-suffix &allow-other-keys)

Test whether the first elements of sequence are the same (as per test) as the elements of prefix. If return-suffix is t the functions returns, as a second value, a displaced array pointing to the sequence after prefix.

 (starts-with-subseq "Dieter" "DieterKaiser") => T, NIL
 (starts-with-subseq "Dieter" "DieterKaiser" :return-suffix t)
=> T
=> "Kaiser"