map over iterator

iter.rs

fn imap<A,B>( i : ~Iterator<A>, f : &fn(A)->B ) { i.map(f) }
fn main () {}
/*
iter.rs:1:50: 1:60 error: type `~std::iterator::Iterator<A>:Send` does not implement any method in scope named `map`
iter.rs:1 fn imap<A,B>( i : ~Iterator<A>, f : &fn(A)->B ) { i.map(f) }
                                                            ^~~~~~~~~~
error: aborting due to previous error
*/