kyo227
kyo227
I've added tests to `test/join.jl` and fixed some bugs.
Thank you for your advice. It seems that my code still has some problems. In this part, I forgot to change this function. So ,the test will not pass. 
I made changes to the implementation of range join in leftjoin and it passed the test in test/join.jl.
Sorry, I found some problems in my code. This code is not ready yet.