title: What does _(variable_name) mean in javascript?
body: <p>I came across the following javascript code:</p>
  
  <pre><code>this.removeEdge = function(source, target) {
    if(!_states[source]) return;
  
    var children = _states[source].children,
        index = _(children).indexOf(target);
    if(index !== -1) children.splice(index, 1);
  };
  </code></pre>
  
  <p>What does _(children) mean?</p>