Update example code to 2018 edition
diff --git a/src/group.rs b/src/group.rs
index 026ece4..d2cbd3e 100644
--- a/src/group.rs
+++ b/src/group.rs
@@ -95,13 +95,10 @@
/// # Example
///
/// ```rust
-/// # #[macro_use]
/// # extern crate quote;
+/// # use quote::quote;
/// #
-/// #[macro_use]
-/// extern crate syn;
-///
-/// use syn::{token, Ident, Result, Type};
+/// use syn::{parenthesized, token, Ident, Result, Token, Type};
/// use syn::parse::{Parse, ParseStream};
/// use syn::punctuated::Punctuated;
///
@@ -156,12 +153,10 @@
/// # Example
///
/// ```rust
-/// # #[macro_use]
/// # extern crate quote;
+/// # use quote::quote;
/// #
-/// #[macro_use]
-/// extern crate syn;
-/// use syn::{token, Ident, Result, Type};
+/// use syn::{braced, token, Ident, Result, Token, Type};
/// use syn::parse::{Parse, ParseStream};
/// use syn::punctuated::Punctuated;
///
@@ -237,16 +232,13 @@
/// # Example
///
/// ```rust
-/// # #[macro_use]
+/// # extern crate proc_macro2;
/// # extern crate quote;
/// #
-/// #[macro_use]
-/// extern crate syn;
-///
-/// extern crate proc_macro2;
-///
+/// # use quote::quote;
+/// #
/// use proc_macro2::TokenStream;
-/// use syn::{token, Result};
+/// use syn::{bracketed, token, Result, Token};
/// use syn::parse::{Parse, ParseStream};
///
/// // Parse an outer attribute like: