title: What argument should pass to other method
body: <p>I'm trying to figure out what argument should be passed to the <code>directors_total</code> method in order to return the results of <code>gross_for_director</code>.</p>
  
  <p>I've tried plugging in different parameters with various error results.</p>
  
  <pre><code>require 'directors_database'
  require 'pp'
  require 'pry'
  
  # Write a method that, given an NDS creates a new Hash
  # The return value should be like:
  #
  # { directorOne =&gt; allTheMoneyTheyMade, ... }
  
  def directors_totals(nds)
    result = {}
    name_index = 0
    director = nds[name_index][:name]
    result[director] = 0
    while name_index &lt; nds.length do
      result[director] += gross_for_director(gross_total)
  
      name_index += 1
    end
  
    result
  end
  
  # Find a way to accumulate the :worldwide_grosses and return that Integer
  # using director_data as input
  def gross_for_director(director_data)
    mov_index = 0
    gross_total = 0
    while mov_index &lt; director_data[:movies].length do
      gross_total += director_data[:movies][mov_index][:worldwide_gross]
  
      mov_index += 1
    end
    gross_total
  end
  
  </code></pre>
  
  <p>The <code>directors_database</code> method can be processed by the <code>directors_totals</code> method which returns a <em>Hash</em> describing director to total.</p>
  
  <pre><code>Failure/Error:
     while mov_index &lt; director_data[:movies].length do
       gross_total += director_data[:movies][mov_index][:worldwide_gross]
  
       mov_index += 1
     end
  
   TypeError:
     no implicit conversion of Symbol into Integer
  </code></pre>
  
  <p>director_ data</p>
  
  <pre><code>   {:name=&gt;"Stephen Spielberg",
   :movies=&gt;
    [{:title=&gt;"Jaws",
      :studio=&gt;"Universal",
      :worldwide_gross=&gt;260000000,
      :release_year=&gt;1975},
     {:title=&gt;"Close Encounters of the Third Kind",
      :studio=&gt;"Columbia",
      :worldwide_gross=&gt;135189114,
      :release_year=&gt;1977},
     {:title=&gt;"Raiders of the Lost Ark",
      :studio=&gt;"Paramount",
      :worldwide_gross=&gt;248159971,
      :release_year=&gt;1981},
     {:title=&gt;"E.T. the Extra-terrestrial",
      :studio=&gt;"Universal",
      :worldwide_gross=&gt;435110554,
      :release_year=&gt;1982},
     {:title=&gt;"Schindler's List",
      :studio=&gt;"Universal",
      :worldwide_gross=&gt;96898818,
      :release_year=&gt;1993},
     {:title=&gt;"Lincoln",
      :studio=&gt;"Buena Vista",
      :worldwide_gross=&gt;182207973,
      :release_year=&gt;2012}]}
  </code></pre>