String-Read!

(string-read! string) -> string
(string-read! string integer) -> string

Returns a string from the contents of the given string, destructively. If an optional integer argument is given, it reads that number of bytes only.

Examples:

>> (define a "This is a test.  This is only a test.")
:: "This is a test.  This is only a test."
>> (string-read! a 15)
:: "This is a test."
>> (string-read! a)
:: "  This is only a test."