julia> Vararg{Int, Union{T,S}} where {T, S}   
julia: /home/vtjnash/julia/src/jltypes.c:933: ijl_type_unionall: Assertion `vm->N == (jl_value_t*)v' failed.
                                                                                                                                                       
[746496] signal 6 (-6): Aborted                                                                                                                        
in expression starting at REPL[1]:1                                                                                                                    
pthread_kill at /lib/x86_64-linux-gnu/libc.so.6 (unknown line)                                                                                         
raise at /lib/x86_64-linux-gnu/libc.so.6 (unknown line)                                                                                                
abort at /lib/x86_64-linux-gnu/libc.so.6 (unknown line)                                                                                                
unknown function (ip: 0x7f46640d571a) at /lib/x86_64-linux-gnu/libc.so.6                                                                               
__assert_fail at /lib/x86_64-linux-gnu/libc.so.6 (unknown line)                                                                                        
ijl_type_unionall at /home/vtjnash/julia/src/jltypes.c:933