title: What do the triple dots (...) in a julia array do? Why do they change the type signature?
body: <p>Given the data types bellow, the following comprehension yields two <code>Array{Any,1}</code> of <code>Player</code>s: </p>
  
  <pre><code>[[team.players for team in [big_team_1, big_team_2]]]
  </code></pre>
  
  <p>This next comprehension, however, yields the desired result of an <code>Array{Player,1}</code> of 12 elements:</p>
  
  <pre><code>[[team.players for team in [big_team_1, big_team_2]]...]
  </code></pre>
  
  <p>What exactly is the <code>...</code> doing? Where is this documented?</p>
  
  <hr>
  
  <p>Data:</p>
  
  <pre><code>type Player
    ranking::Int
  end
  
  type Team
    players::Array{Player}
  end
  
  team_1 = Team([Player(10_000), Player(11_000), Player(9_000), Player(8_500),
                     Player(20_000), Player(10_500)])
  
  team_2 = Team([Player(i.ranking + 3000) for i in team_1.players])
  </code></pre>