Pihrtsoft.Text.RegularExpressions.Linq.Chars.AlphanumericUnderscore C# (CSharp) Method

        public static CharGrouping AlphanumericUnderscore() => Alphanumeric().Underscore();

 /// <summary>
 /// Appends a pattern that matches a latin alphabet letter, an arabic digit or an underscore.
 /// </summary>
 /// <returns></returns>
 public CharGrouping AlphanumericUnderscore() => Append(Chars.AlphanumericUnderscore());