Vars

using System;
using static AngouriMath.MathS;

var (x, y) = Var("x", "y");
var expr1 = Lambda(x, x * 2 + Sin(y * pi));
Console.WriteLine(expr1);
Console.WriteLine("Variables:");
foreach (var var in expr1.Vars)
    Console.WriteLine($"  {var}");
Console.WriteLine("Variables and constants:");
foreach (var var in expr1.VarsAndConsts)
    Console.WriteLine($"  {var}");
Console.WriteLine("Only free variables:");
foreach (var var in expr1.FreeVariables)
    Console.WriteLine($"  {var}");

x -> x * 2 + sin(y * pi)
Variables:
  x
  y
Variables and constants:
  x
  y
  pi
Only free variables:
  y
  pi