title: Regex to match combination of letter and numbers to be used in URL pattarns in Django Project?
body: <p>I need to pass username in my URL.
  username can be any combination of letter, numbers and special characters like <code>@</code>,<code>_</code>.
  also, username starts with a letter.</p>
  
  <p>username examples: <code>test@1, test_1,test2_1990,</code> </p>