"Step" is a static-call to an extension method. This way allows your code to keep working fine (unchanged) for users that aren't profiling (i.e. 99.99% of the users).
Strange, but does enable some interesting syntactic sugar checking for empty values etc.
So then you can say if(foo.Exists()) { foo.bar(); }
Or make Exists return an instance of Foo (foo if not null, a new Foo if not) and go with foo.Exists().bar();