title: When to use leading underscore in variable names in Go
body: <p>Is there any special purpose of leading <code>_</code> in a variable's name?</p>
  
  <p>Example:
  <code>func (_m *MockTracker)...</code> </p>
  
  <p>from <a href="https://github.com/fluffle/goirc/blob/master/state/mock_tracker.go" rel="noreferrer">here</a>. </p>