title: Regex not beginning with number
body: <p>How do I create a regex that matches all alphanumerics without a number at the beginning?</p>
  
  <p>Right now I have <code>"^[0-9][a-zA-Z0-9_]"</code></p>
  
  <p>For example, 1ab would not match, ab1 would match, 1_bc would not match, bc_1 would match.</p>