Understanding Python function arg notation like this: str.find(sub[, start[, end]])
<p>Can someone describe what's happening syntactically in functions like functions like <code>str.find(sub[, start[, end]])</code>? I don't understand what the function arguments are doing or supposed to be. </p>

<p>For one thing, what is the <code>[, x]</code> construct? </p>
