How to comment out a block of code in Python

Python does not have such a mechanism. Prepend a # to each line to block comment. For more information see PEP 8. Most Python IDEs support a mechanism to do the block-commenting-with-hash-signs automatically for you. For example, in IDLE on my machine, it's Alt+3 and Alt+4.

Don't use triple-quotes; as you discovered, this is for documentation strings not block comments, although it has a similar effect. If you're just commenting things out temporarily, this is fine as a temporary measure.

Hide the triple quotes in a context that won't be mistaken for a docstring, eg:

'''
...statements...
''' and None

or:

if False: '''
...statements...
'''

The only cure I know for this is a good editor. Sorry.

The only way you can do this without triple quotes is to add an:

if False:

And then indent all your code. Note that the code will still need to have proper syntax.

Many Python IDEs can add # for you on each selected line, and remove them when un-commenting too. Likewise, if you use vi or Emacs you can create a macro to do this for you for a block of code.