title: optional argument Python
body: <p>Have to write some code that defines a function that will work with two or three arguments.</p>
  <p>The function should take three parameters:</p>
  <ul>
  <li>temperature, a float</li>
  <li>weather, a string</li>
  <li>is_celsius, a boolean</li>
  </ul>
  <p>The function should return True if temperature is below
  freezing (32 if is_celsius is False, 0 if is_celsius is
  True) or if weather is &quot;snowy&quot;. Otherwise, it should
  return False.</p>
  <p>Note, however, that is_celsius should be an optional
  argument. If the function call does not supply a value for
  is_celsius, assume it is True.</p>
  <p>I wrote this</p>
  <pre><code>def snowed_in(temperature, weather, **cels):
      if weather ==&quot;snowy&quot;:
          return True
      elif weather==&quot;sunny&quot;:
          if 'is_celsius = False' in cels:
              if temperature&lt;32:
                  return True
      elif 'is_celsius = True' in cels:
          if temperature&lt;0:
              print ('ad')    
              return True
      elif 'is_celsius = True' not in cels:
          if temperature&lt;0:
              return True
      else:
          return False
  </code></pre>
  <p>and for the following calls</p>
  <pre><code>print(snowed_in(15, &quot;sunny&quot;)) #Should print False
  print(snowed_in(15, &quot;sunny&quot;,is_celsius = False)) #Should print True
  print(snowed_in(15, &quot;snowy&quot;,is_celsius = True)) #Should print True
  </code></pre>
  <p>I'm getting</p>
  <pre><code>None
  None
  True
  </code></pre>
  <p>Can someone help me find what's wrong with my code?</p>