# File lib/AWS/EC2/instances.rb, line 211
211:       def monitor_instances( options = {} )
212:         options = { :instance_id => [] }.merge(options)
213:         raise ArgumentError, "No :instance_id provided" if options[:instance_id].nil? || options[:instance_id].empty?
214:         params = pathlist("InstanceId", options[:instance_id])
215:         return response_generator(:action => "MonitorInstances", :params => params)
216:       end