public Task<Mapping> EditMapping(Mapping mapping)
        {
            var definitions = sites
                .FirstOrDefault(site => site.Id == mapping.SiteId)
                .MappingDefinitions;

            var modifiedDefinitions = definitions.Select(definition => {
                    return definition.Mappings
                    .Select(x => x.Id == mapping.Id ? mapping : x)
                    .ToList();
                })
                .ToList();


            var modifiedDefinitions = definitions.Aggregate(new List<MappingDefinition>(), (mappingDefinitions, definition) => {
                definition.Mappings = definition.Mappings
                    .Select(x => x.Id == mapping.Id ? mapping : x)
                    .ToList();

                var exisitingDefinitions = mappingDefinitions;

                exisitingDefinitions.Add(definition);

                return exisitingDefinitions;
            });

            // Please note. Stuff like this is only because we do not have a DB to store it on
            // Our current data is a big long ass object
            sites.FirstOrDefault(site => site.Id == mapping.SiteId).MappingDefinitions = modifiedDefinitions;

            return Task.FromResult(mapping);
        }

public