title: no method matching in subtraction
body: <p>I'm using julia 0.5 after run this code :</p>
  
  <pre><code>Freqsample = 100;
  second = 4;
  step = (Freqsample * second )-1
  </code></pre>
  
  <p>i get this Error :</p>
  
  <pre><code>MethodError: no method matching getindex(::Int64, ::Colon, ::UnitRange{Int64})
   in -(::Int64, ::Int64) at main.jl:12
   in include_string(::String, ::String) at loading.jl:441
   in eval(::Module, ::Any) at boot.jl:234
   in (::Atom.##65#68)() at eval.jl:40
   in withpath(::Atom.##65#68, ::Void) at utils.jl:30
   in withpath(::Function, ::Void) at eval.jl:46
   in macro expansion at eval.jl:109 [inlined]
   in (::Atom.##64#67{Dict{String,Any}})() at task.jl:60
  </code></pre>
  
  <p>Whats wrong with subtracting ? i'm pretty new to julia forgive if its a dumb question</p>