title: How to determine if Julia object is callable
body: <p>In Julia, what's the best way to determine whether an object is callable?  (E.g. is there an analog of python's <code>callable</code> function?)</p>
  
  <p>EDIT: Here's what one could wish for:</p>
  
  <pre><code>f() = println("Hi")
  x = [1,2,3]
  a = 'A'
  
  callable(f)    # =&gt; true
  callable(x)    # =&gt; false
  callable(a)    # =&gt; false
  callable(sin)  # =&gt; true
  </code></pre>