title: Python Handling Undeclared Variables
body: <p>In Python is it possible to avoid a variable (pre-) declaration to avoid a <em>NameError: name 'c' is not defined</em>:</p>
  
  <pre><code>a=5
  if a==7:
      c=10
  if c: print c
  </code></pre>
  
  <p>On a last line <strong><em>if c:</em></strong> simply verifies if variable '<strong><em>c</em></strong>' is not None. What can be used to check if 'c' variable even exist (or was pre-declared)?</p>