docs: function add_stub_for(prototype, stub) {
      function method_missing_stub() {
        // Copy any given block onto the method_missing dispatcher
        this.$method_missing._p = method_missing_stub._p;
  
        // Set block property to null ready for the next call (stop false-positives)
        method_missing_stub._p = null;
  
        // call method missing with correct args (remove '$' prefix on method name)
        return this.$method_missing.apply(this, [stub.slice(1)].concat($slice.call(arguments)));
      }
  
      method_missing_stub.rb_stub = true;
      prototype[stub] = method_missing_stub;
    }