code: function( timeout, success, message ) {
  		var logMessage = "Waiting for '"+this.selector+"' to exist";
  		if(timeout === false){ // pass false to suppress this wait (make it not print any logMessage)
  			logMessage = false
  		}
  		return this.size({
  			condition: function(size){
  				return size > 0;
  			},
  			timeout: timeout,
  			success: success,
  			message: message,
  			errorMessage: "Exist failed: element with selector '"+this.selector+"' not found",
  			logMessage: logMessage
  		})
  	}
docs: Waits until an element exists before running the next action.
  @codestart
  //waits until #foo exists before clicking it.
  S("#foo").exists().click()
  @codeend
  @param {Number} [timeout] overrides FuncUnit.timeout.  If provided, the wait will fail if not completed before this timeout.
  @param {Function} [success] a success that is run after the selector exists, but before the next action.
  @param {String} [message] if provided, an assertion will be passed when this wait condition completes successfully
  @return {FuncUnit} returns the funcUnit for chaining.