Merge pull request #909 from luidnel-maignan/patch-1

A simple missing space

Author: ehuss

src/expressions/call-expr.md

@@ -68,7 +68,7 @@ struct Bar;
 impl Pretty for Bar {
     fn print(&self) {}
 }
-impl Ugly for Bar{
+impl Ugly for Bar {
     fn print(&self) {}
 }