title: function default value not defined
body: <p>I'm trying to use</p>
  <pre><code>def my_function(a,b)
  </code></pre>
  <p>If I  try to print function like this
  <code>print(my_function())</code>, when values start from none, I get
  &quot;missing 2 required positional arguments&quot;</p>
  <p>I want to use default value so when I use, <code>print(my_function())</code>,
  <code>a=10</code> and <code>b=a</code>.</p>
  <p>So I tried</p>
  <pre><code>def my_function(a=10,b=a)
  </code></pre>
  <p>and I got <code>a not defined</code>.</p>
  <p>I don't want to define <code>a</code> before with global.</p>
  <p>Is it possible? or something like this</p>
  <pre><code>def my_function(a,b)
      if a == None:
          a = 10
      if b == None:
          b = a
  </code></pre>
  <p>This didn't work either when I used <code>print(my_function())</code>.</p>