title: Modifying global variable with same name as local variable
body: <p>Suppose I have a global variable <code>a</code>. And within a function definition, we also have a local variable named <code>a</code>. Is there any way to assign the value of the global variable to that of the local variable?</p>
  
  <pre><code>a = 'foo'
  
  def my_func(a = 'bar'):
      # how to set global a to value of the local a?
  </code></pre>