title: ERROR: need type assertion
body: <p>I thought I have asserted (as far as I've learnt Go), but I keep getting this error
  <code>cannot use readBack["SomePIN"] (type interface {}) as type string in argument to c.String: need type assertion</code></p>
  
  <p>Here is my code (this snippet is from a Request Handler function and I'm using Echo Web framework and Tiedot NoSQL database)</p>
  
  <pre><code>// To get query result document, simply 
  // read it [as stated in the Tiedot readme.md]
  for id := range queryResult {
      readBack, err := aCollection.Read(id)
      if err != nil {
          panic(err)
      }
      if readBack["OtherID"] == otherID {
          if _, ok := readBack["SomePIN"].(string); ok {
              return c.String(http.StatusOK, readBack["SomePIN"])
          }
      }
  }
  </code></pre>