added assert example

examples/assert.js

@@ -0,0 +1,31 @@
+
+require('../');
+
+var fs = require('fs');
+
+function assert(expr) {
+  if (expr) return;
+
+  var call = __stack[1]
+    , file = call.getFileName()
+    , lineno = call.getLineNumber()
+    , src = fs.readFileSync(file, 'utf8')
+    , line = src.split('\n')[lineno-1]
+    , src = parse(line);
+
+  var fmt = '  \033[91massert: \033[31m%s\033[0m'
+    + '\033[90m in %s:%d\033[0m';
+
+  console.error(fmt, src, file, lineno);
+}
+
+function parse(str) {
+  return str.match(/assert\((.*)\)/)[1];
+}
+
+assert('wahoo');
+
+var user = { authenticated: false };
+assert(user.authenticated);
+
+