Member predicate API::Node::asCallable

Gets a callable that can reach this sink.

For example:

Foo.bar do |x| # API::getTopLevelMember("Foo").getMethod("bar").getBlock().asCallable()
end

class Baz
  def m # API::getTopLevelMember("Foo").getMethod("bar").getArgument(0).getMethod("m").asCallable()
  end
end
Foo.bar(Baz.new)