Started working on the aggregate/reduce method
simplifying aggregate
Revising my implementation of range and the associated tests to make it more like LINQ
polishing aggregate after revising LINQ implementation
Implementing custom seed values and result selector
Implementing the average method
Decided I didn't like the test grouping so ungrouped them all
Implementing the concat method for both enumable and array
Missed a semicolon
Implementing the contains method which handles custom equality testing