as the "Migos Flow" (a term that is contentious within the hip-hop community). Rap notation and flow diagrams The standard form of rap notation is the flow diagram, where rappers line-up their lyrics underneath "beat numbers". Different rappers have slightly different forms of flow diagram that they use: Del the Funky Homosapien says, "I'm just writing out the rhythm of the flow, basically. Even if it's just slashes to represent the beats, that's enough to give me a visual path.", Vinnie Paz states, "I've created my own sort of writing technique, like little marks and asterisks to show like a pause or emphasis on words in certain places.", and Aesop Rock says, "I have a system of maybe 10 little symbols that I use on paper that tell me to do something when I'm recording." Hip-hop scholars also make use of the same flow diagrams: the books How to Rap and How to Rap 2 use the diagrams to explain rap's triplets, flams, rests, rhyme schemes, runs of rhyme, and breaking rhyme patterns, among other techniques. Similar systems are used by PhD musicologists Adam Krims in his book Rap Music and the Poetics of Identity and Kyle Adams in his academic work on flow. Because rap revolves around a strong 4/4 beat, with certain syllables said in time to the beat, all the notational systems have a similar structure: they all have the same 4 beat numbers at the top of the diagram, so that syllables can be written in-line with the beat numbers. This allows devices such as rests, "lazy tails", flams, and other rhythmic techniques to be shown, as well as illustrating where different rhyming words fall in relation to the music. Performance To successfully deliver a rap, a rapper must also develop vocal presence, enunciation, and breath control. Vocal presence is the distinctiveness of a rapper's voice on record. Enunciation is essential to a flowing rap; some rappers choose also to exaggerate it for comic and artistic effect. Breath control, taking in air without interrupting one's delivery, is an important skill for a rapper to master, and a must for any MC. An MC with poor breath control cannot deliver difficult verses without making unintentional pauses. Raps are sometimes delivered with melody. West Coast rapper Egyptian Lover was the first notable MC to deliver "sing-raps". Popular rappers such as 50 Cent and Ja Rule add a slight