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copied!<p>I only use <code>assert</code>s if they provide far better diagnostics than the error messages that I would get otherwise. Your third assert</p> <pre><code>assert(callable(func)) </code></pre> <p>might be an example for such an assert -- if <code>func</code> is not callable, you will get an error message at a completely different line of code than where the actual error is, and it might not be obvious how the non-callable object ended up in <code>self.symbols_map</code>. I write "might" because this depends on the rest of your code -- if this is the only place where <code>self.symbols_map</code> gets updated, the assert might also be unnecessary.</p> <p>The first and last assert definitely are against the idea of duck-typing, <s>and the second one is redundant. If <code>symbol</code> isn't a string of length 1, chances are that <code>self.symbols_map[symbol]</code> will raise a <code>KeyError</code> anyway, so no need for the asserts.</s></p> <p>The last assert is also wrong -- <code>type(keypress)</code> cannot be <code>None</code>, and type checks should be done with <code>isinstance()</code>. There might be very specialised applications where you cannot allow subtypes, but than the check should be performed with <code>type(x) is int</code> instead of <code>type(x) == int</code>. Checking for <code>None</code> should be done by <code>x is None</code>, not by <code>type(x) is NoneType</code>.</p> <p>You should probably write a good set of unit tests -- they will be far more useful than the asserts, and might make almost all of your asserts redundant.</p>

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