Developer's-corner/Boundary-Conditions.md

@@ -90,9 +90,9 @@ They will be made available to the code through a [std::map](http://www.cplusplu
 ```
  void
  PetShopBC(GasDisk& gas, real dt) {
-    using namespace std;
-    map<string, string> const& params = gas.physic().boundaries.params;
-    real voltage = boost::lexical_cast<real>(attrs["voltage"]);
+   
+    std::map<std::string, std::string> const& params = gas.physic().boundaries.params;
+    real voltage = boost::lexical_cast<real>(attrs.at("voltage"));
     string type  = attrs["type"];
     ...
  }