Start your Python 3 interpreter:
If on Windows or:
On Mac or Linux.
The control flow structures of Python, such as for-loops, while-loops, and if-statements, are all introduced by statements which are terminated by a colon, indicating that the body of the construct is to follow. For example, for-loops require a body, so if you enter:
>>> for i in range(5):...
Python will present you with a prompt of three dots to request that you provide the body. One distinctive (and sometimes controversial) aspect of Python is that leading whitespace is syntactically significant.
What this means is that Python uses indentation levels, rather the braces used by other languages, to demarcate ...