public static IEnumerable <SearchItem> Apply(SearchExpressionContext c)
        {
            if (c.args.Length == 0)
            {
                c.ThrowError("Invalid Arguments");
            }

            var resultStreamExpr = c.args[0];

            if (!resultStreamExpr.types.IsIterable())
            {
                c.ThrowError($"No iterators", resultStreamExpr.outerText);
            }

            var exprs = new List <SearchExpression>(c.expression.parameters.Length);

            for (var i = 1; i < c.expression.parameters.Length; ++i)
            {
                var templateExpr = c.expression.parameters[i];
                var currentStreamName = $"apply@stream#{i}";
                var currentStream = SearchExpression.CreateStreamExpression(resultStreamExpr, currentStreamName);
                var args = new[] { currentStream }.Concat(templateExpr.parameters).ToArray();
                var innerText = templateExpr.innerText;
                var evaluator = templateExpr.evaluator;

                if (templateExpr.types.HasFlag(SearchExpressionType.Function))
                {
                    // Back patch arguments
                    var restOfArguments = templateExpr.innerText.Substring(templateExpr.evaluator.name.Length + 1);
                    innerText = $"{templateExpr.evaluator.name}{{{currentStreamName}, {restOfArguments}}}".GetStringView();
                }
                else if (templateExpr.types.HasFlag(SearchExpressionType.Text))
                {
                    // String literal used as an evaluator name:
                    var filterFunction = EvaluatorManager.GetEvaluatorByNameDuringEvaluation(templateExpr.innerText.ToString(), templateExpr.innerText, c);
                    innerText = $"{templateExpr.innerText}{{{currentStreamName}}}".GetStringView();
                    evaluator = filterFunction;
                }
                else
                {
                    c.ThrowError($"Bad argument type", templateExpr.outerText);
                }

                var patchedExpr = new SearchExpression(templateExpr.types, templateExpr.outerText, innerText, evaluator, args);
                exprs.Add(patchedExpr);
                resultStreamExpr = patchedExpr;
            }

            // Pull on the last element to start the evaluation chain
            return(exprs.Last().Execute(c));
        }