pub fn from_utf8_opt(vv: &[u8]) -> Option<~str>
Convert a vector of bytes to a new UTF-8 string, if possible. Returns None if the vector contains invalid UTF-8.
Prefix searches with a type followed by a colon (e.g.
fn:) to restrict the search to a given type.
Accepted types are: fn, mod,
struct (or str), enum,
trait, typedef (or
tdef).