What Python Adds

The one new syntax component in Python is the colon character (:). All Python compound statements (i.e., statements that have statements nested inside them) follow the same general pattern of a header line terminated in a colon, followed by a nested block of code usually indented underneath the header line, like this:

Header line:
    Nested statement block

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The colon is required, and omitting it is probably the most common coding mistake among new Python programmers—it’s certainly one I’ve witnessed thousands of times in Python training classes. In fact, if you are new to Python, you’ll almost certainly forget the colon character very soon. Most Python-friendly editors make this mistake easy to spot, and including it eventually becomes an unconscious habit (so much so that you may start typing colons in your C++ code, too, generating many entertaining error messages from your C++ compiler!).