C# Tuple assignement Regex

Helpers.cs

using System;
using System.Linq;
using System.Text.RegularExpressions;
using System.Text;

string str = @"
a1 = b1;
a2 = b2;
a3 = b3;";

var matches = new Regex(@"\s*(\S+) = (\S+);").Matches(str);

Console.WriteLine(new StringBuilder("(")
    .AppendJoin(", ", matches.Select(m => m.Groups[1].Value))
    .Append(") = (")
    .AppendJoin(", ", matches.Select(m => m.Groups[2].Value))
    .Append(')'));