title: Using cython .pxd files to Augment pure python files
body: <p>Following the example here, "<a href="http://docs.cython.org/src/tutorial/pure.html?highlight=pxd#augmenting-pxd" rel="noreferrer">Augementing .pxd</a>", I'm trying to use ".pxd" files to augment a pure python file. (Add type definitions external to the pure python file).</p>
  
  <p>python file:</p>
  
  <pre><code>class A(object):
      def foo(self, i=3, x=None):
          print "Big" if i &gt; 1000 else "Small"
  </code></pre>
  
  <p>pxd file:</p>
  
  <pre><code>cdef class A:
      cpdef foo(self, int i, x)
  </code></pre>
  
  <p>I've got a dictionary, which I'm defaulting to "None" in python.
  Unfortunately, cython doesn't like this.</p>
  
  <p>If I use my "pure" python file, without declaring a type or declare the type as "dict" in the pxd file I get the error:</p>
  
  <blockquote>
    <p><em>"Signature not compatible with previous declaration"</em></p>
  </blockquote>
  
  <p>I noticed that it will compile if I do NOT specify a default value, but there's a reason for declaring the defaults.  </p>
  
  <p>Is there a way this can be handled?</p>