title: key holding wrong kind of value in redis when pushing data on a list
body: <p>I am trying redis on my heroku app.  I have the following code in <code>config/initializers/redis.rb</code></p>
  
  <pre><code>uri = URI.parse(ENV["REDISTOGO_URL"])
  REDIS = Redis.new(:host =&gt; uri.host, :port =&gt; uri.port, :password =&gt; uri.password)
  </code></pre>
  
  <p>I'm trying the following in the console but getting error:</p>
  
  <pre><code>irb(main):003:0&gt; REDIS.rpush ('foo','bar')
  (irb):3: warning: don't put space before argument parentheses
  RuntimeError: -ERR Operation against a key holding the wrong kind of value
  </code></pre>