See if some string literal occurs (case insensitively) at the start of the input stream.
We just leave this enabled.
Function:
(defun strin-imatches-p (lit x) (declare (xargs :guard (and (stringp lit) (strin-p x)))) (let ((__function__ 'strin-imatches-p)) (declare (ignorable __function__)) (str::iprefixp (coerce lit 'list) (strin-left x))))