replace leading _ for private symbols with keyword hide

examples/programs/io/main.bro

@@ -1,6 +1,6 @@
 io :: import "@std/io"
 
-_read_ok func(_ ?*mut anyopaque, _ io.ReadStream, buffer []mut u8) usize ! io.ReadError {
+hide read_ok func(_ ?*mut anyopaque, _ io.ReadStream, buffer []mut u8) usize ! io.ReadError {
 	if buffer.len == 0 {
 		return 0
 	}
@@ -12,52 +12,52 @@ _read_ok func(_ ?*mut anyopaque, _ io.ReadStream, buffer []mut u8) usize ! io.Re
 	return 2
 }
 
-_read_too_much func(_ ?*mut anyopaque, _ io.ReadStream, buffer []mut u8) usize ! io.ReadError {
+hide read_too_much func(_ ?*mut anyopaque, _ io.ReadStream, buffer []mut u8) usize ! io.ReadError {
 	return buffer.len + 1
 }
 
-_read_eof func(_ ?*mut anyopaque, _ io.ReadStream, _ []mut u8) usize ! io.ReadError {
+hide read_eof func(_ ?*mut anyopaque, _ io.ReadStream, _ []mut u8) usize ! io.ReadError {
 	return 0
 }
 
-_write_short func(_ ?*mut anyopaque, _ io.WriteStream, bytes []u8) usize ! io.WriteError {
+hide write_short func(_ ?*mut anyopaque, _ io.WriteStream, bytes []u8) usize ! io.WriteError {
 	if bytes.len > 2 {
 		return 2
 	}
 	return bytes.len
 }
 
-_write_none func(_ ?*mut anyopaque, _ io.WriteStream, _ []u8) usize ! io.WriteError {
+hide write_none func(_ ?*mut anyopaque, _ io.WriteStream, _ []u8) usize ! io.WriteError {
 	return 0
 }
 
-_write_too_much func(_ ?*mut anyopaque, _ io.WriteStream, bytes []u8) usize ! io.WriteError {
+hide write_too_much func(_ ?*mut anyopaque, _ io.WriteStream, bytes []u8) usize ! io.WriteError {
 	return bytes.len + 1
 }
 
-_ok_vtable io.IoVTable :: io.IoVTable {
-	read = _read_ok,
-	write = _write_short,
+hide ok_vtable io.IoVTable :: io.IoVTable {
+	read = read_ok,
+	write = write_short,
 }
 
-_read_bad_vtable io.IoVTable :: io.IoVTable {
-	read = _read_too_much,
-	write = _write_short,
+hide read_bad_vtable io.IoVTable :: io.IoVTable {
+	read = read_too_much,
+	write = write_short,
 }
 
-_eof_vtable io.IoVTable :: io.IoVTable {
-	read = _read_eof,
-	write = _write_short,
+hide eof_vtable io.IoVTable :: io.IoVTable {
+	read = read_eof,
+	write = write_short,
 }
 
-_write_none_vtable io.IoVTable :: io.IoVTable {
-	read = _read_ok,
-	write = _write_none,
+hide write_none_vtable io.IoVTable :: io.IoVTable {
+	read = read_ok,
+	write = write_none,
 }
 
-_write_bad_vtable io.IoVTable :: io.IoVTable {
-	read = _read_ok,
-	write = _write_too_much,
+hide write_bad_vtable io.IoVTable :: io.IoVTable {
+	read = read_ok,
+	write = write_too_much,
 }
 
 reader_for func(vtable @io.IoVTable) io.Reader {
@@ -76,39 +76,39 @@ writer_for func(vtable @io.IoVTable) io.Writer {
 
 rejects_bad_read func() bool {
 	buffer [1]mut u8 = [0]
-	_ = io.read(reader_for(&_read_bad_vtable), buffer[..]) catch |err| {
+	_ = io.read(reader_for(&read_bad_vtable), buffer[..]) catch |err| {
 		return err == .read_failed
 	}
 	return false
 }
 
 rejects_no_progress func() bool {
-	io.write_all(writer_for(&_write_none_vtable), "x") catch |err| {
+	io.write_all(writer_for(&write_none_vtable), "x") catch |err| {
 		return err == .no_progress
 	}
 	return false
 }
 
 rejects_bad_write func() bool {
-	_ = io.write(writer_for(&_write_bad_vtable), "x") catch |err| {
+	_ = io.write(writer_for(&write_bad_vtable), "x") catch |err| {
 		return err == .write_failed
 	}
 	return false
 }
 
-main func(system io.Io) i32 {
+main func(system std.Io) i32 {
 	buffer [2]mut u8 = [0, 0]
-	count usize :: io.read(reader_for(&_ok_vtable), buffer[..]) catch 0
+	count usize :: io.read(reader_for(&ok_vtable), buffer[..]) catch 0
 	if count != 2 or buffer[0] != 'o' or buffer[1] != 'k' {
 		return 1
 	}
-	eof usize :: io.read(reader_for(&_eof_vtable), buffer[..]) catch 1
-	empty_read usize :: io.read(reader_for(&_read_bad_vtable), buffer[0..0]) catch 1
-	empty_write usize :: io.write(writer_for(&_write_bad_vtable), "") catch 1
+	eof usize :: io.read(reader_for(&eof_vtable), buffer[..]) catch 1
+	empty_read usize :: io.read(reader_for(&read_bad_vtable), buffer[0..0]) catch 1
+	empty_write usize :: io.write(writer_for(&write_bad_vtable), "") catch 1
 	if eof != 0 or empty_read != 0 or empty_write != 0 {
 		return 5
 	}
-	io.write_all(writer_for(&_ok_vtable), "partial") catch |_| {
+	io.write_all(writer_for(&ok_vtable), "partial") catch |_| {
 		return 2
 	}
 	if !rejects_bad_read() or !rejects_no_progress() or !rejects_bad_write() {