My kids do this at a rapid fire pace, leaving me no response time. Still my usual response is, "Yes honey, I'm right here. What do you need?" said kindly the first few times in the day.
Then by early evening and this has been going on all day for everything they want, need and with the rapid fire "Mom, Mom, Mommy, Mommy, Mom,Mom,Mom, MOM! Mommy..." I have to interrupt them and say "What!! I'm right here, just talk to me!!"