System.Linq.Expressions.Expression.MakeBinary C# (CSharp) Method

        public static BinaryExpression MakeBinary(ExpressionType binaryType, Expression left, Expression right)
        {
            return MakeBinary(binaryType, left, right, liftToNull: false, method: null, conversion: null);
        }

        private LambdaExpression fromEnumerableLambda(Type from)
        {
            var input = Ex.Parameter(from, "input");
            var eType = from.GetTypeInfo().ImplementedInterfaces
                        .Where(i => i.GenericTypeArguments.Length == 1 && i.GetGenericTypeDefinition() == typeof(IEnumerable <>))
                        .Select(i => i.GenericTypeArguments[0]).SingleOrDefault()
                        ?? from.GetTypeInfo().GenericTypeArguments[0];
            var res    = Ex.Parameter(typeof(string), "res");
            var result = Ex.Block(new[] { res },
                                  Ex.Assign(res, Ex.Call((from mi in typeof(string).GetTypeInfo().GetDeclaredMethods(nameof(string.Join))
                                                          where mi.GetGenericArguments().Length == 1
                                                          let par = mi.GetParameters()
                                                                    where par.Length == 2 &&
                                                                    par[0].ParameterType == typeof(string) &&
                                                                    par[1].ParameterType == typeof(IEnumerable <>).MakeGenericType(mi.GetGenericArguments()[0])
                                                                    select mi).Single().MakeGenericMethod(eType),
                                                         Ex.Constant(Separators[0].ToString()), input)),
                                  Ex.Condition(Ex.MakeBinary(Et.Equal, Ex.Property(res, nameof(string.Length)), Ex.Constant(0)),
                                               NoResult(typeof(string)),
                                               Result(typeof(string), res)));

            var block = Ex.Condition(Ex.MakeBinary(Et.Equal, input, Ex.Default(from)),
                                     NoResult(typeof(string)),
                                     result);
            var lambda = Ex.Lambda(block, input);

            return(lambda);
        }