More concise way to append a value to a dict array-element?
<p>When I want to append a newvalue into Dict under Key, I find myself have to write:</p>

<pre><code># Dict={}
# Key = ....
# newvalue = ....

if not Key in Dict:
    Dict[Key] = [ newvalue ]
else:
    Dict[Key].append(newvalue)
</code></pre>

<p>It costs four lines of code. Is there a more concise way with python standard library? e.g </p>

<pre><code>Dict.appendkeyvalue(Key, newvalue)
</code></pre>
