add chapter [Advanced use and pub]

solutions/crate-module/use-pub.md

@@ -0,0 +1,39 @@
+1.
+```rust
+use std::fmt::Result;
+use std::io::Result as IoResult;
+
+fn main() {}
+```
+
+2.
+```rust
+use std::collections::*;
+
+fn main() {
+    let _c1:HashMap<&str, i32> = HashMap::new();
+    let mut c2 = BTreeMap::new();
+    c2.insert(1, "a");
+    let _c3: HashSet<i32> = HashSet::new();
+}
+```
+
+```rust
+use std::collections::{HashMap, BTreeMap, HashSet};
+
+fn main() {
+    let _c1:HashMap<&str, i32> = HashMap::new();
+    let mut c2 = BTreeMap::new();
+    c2.insert(1, "a");
+    let _c3: HashSet<i32> = HashSet::new();
+}
+```
+
+
+3. 
+```rust
+// in lib.rs
+
+// Add this line
+pub use crate::front_of_house::hosting;
+```

src/crate-module/use-pub.md

@@ -1 +1,66 @@
 # use and pub
+1. 🌟 We can bring two types of the same name into the same scope with use, but you need `as` keyword.
+
+```rust,editable
+use std::fmt::Result;
+use std::io::Result;
+
+fn main() {}
+```
+
+2. 🌟🌟 If we are using multiple items defined in the same crate or module, then listing each item on its own line will take up too much verticall space.
+
+```rust,editable
+
+// FILL in the blank in two ways
+// DON'T add new code line
+use std::collections::__;
+
+fn main() {
+    let _c1:HashMap<&str, i32> = HashMap::new();
+    let mut c2 = BTreeMap::new();
+    c2.insert(1, "a");
+    let _c3: HashSet<i32> = HashSet::new();
+}
+```
+
+### Re-exporting names with `pub use`
+3. 🌟🌟🌟 In our recently created package `hello-package`, add something to make the below code work
+```rust,editable
+fn main() {
+    assert_eq!(hello_package::hosting::seat_at_table(), "sit down please");
+     assert_eq!(hello_package::eat_at_restaurant(),"yummy yummy!");
+}
+```
+
+
+### pub(in Crate) 
+Sometimes we want an item only be public to a certain crate, then we can use the `pub(in Crate)` syntax.
+
+#### Example
+```rust,editable
+pub mod a {
+    pub const I: i32 = 3;
+
+    fn semisecret(x: i32) -> i32 {
+        use self::b::c::J;
+        x + J
+    }
+
+    pub fn bar(z: i32) -> i32 {
+        semisecret(I) * z
+    }
+    pub fn foo(y: i32) -> i32 {
+        semisecret(I) + y
+    }
+
+    mod b {
+        pub(in crate::a) mod c {
+            pub(in crate::a) const J: i32 = 4;
+        }
+    }
+}
+```
+
+### Full Code
+The full code of `hello-package` is [here](https://github.com/sunface/rust-by-practice/tree/master/practices/hello-package).