flowchart LR
  Start[Start]
  Stop[Stop]
  Loop(( ))
  Prefix(( ))
  Start --> Prefix
  Start --> Esc([<tt>&amp;</tt>]) --> Prefix
  Prefix --> Letter{{A..Z, a..z}} --> Loop
  Prefix --> Under([_]) --> Loop
  Loop --> Letter2{{A..Z, a..z}} --> Loop
  Loop --> Under2([_]) --> Loop
  Loop --> Digit{{0..9}} --> Loop
  Loop --> Stop