Sorted using `isort`. Sorted alphabetically, with sections for standard
library, third-party, and then internal imports.

comparison to None should be 'if cond is None:' or 'if cond is not None:'

statement ends with a semicolon

the backslash is redundant between brackets

line too long (> 79 characters)

blank line at end of file

too many blank lines

expected 2 blank lines, found 1 (above module level defined classes and
functions)

expected 1 blank line, found 0

blank line contains whitespace

trailing whitespace

at least two spaces before inline comment

missing whitespace after ':'
missing whitespace after ','

missing whitespace around operator

multiple spaces before operator

whitespace before ':'

whitespace before ')'

whitespace after '('

continuation line under-indented for visual indent

continuation line over-indented for visual indent

continuation line with same indent as next logical line

This allows the default discover on unittest to work

Summarizing:

1. Separate subject from body with a blank line
2. Limit the subject line to 50 characters
3. Capitalize the subject line
4. Do not end the subject line with a period
5. Use the imperative mood in the subject line
6. Wrap the body at 72 characters
7. Use the body to explain what and why vs. how

The expression in the PrettyPrinterHideTagFilter expects that tag names
don't have any spaces around them, but this could be the case when
adding this to the configuration file:

 hide_tags = p, id

So make sure to strip off all spaces from tag names before passing them
along.

It's a 4 year old version of Python and some libraries are no longer
supporting it anymore. This removes some hairy code to support Python
3.2 any longer.

It has a backward incompatible change to rename the get_input() function
to prompt(). For now it's still supported, but it's better to anticipate
the removal of get_prompt() in the (near?) future.

Much more powerful filtering of priorities

Now it is possible to do things like:

`ls (>C)`  # gives items with A-B priorities
`ls (<=D)` # gives items with D-Z priorities
`ls (!E)`  # gives all items except those with E priority (also possible
           # with `ls -- -(E)`

and maybe most importantly:
`ls (<Z)` # gives items without priority

PS Don't forget about escaping parentheses when calling from CLI

Move core functionality of Filter.OrdinalTagFilter to it for possible
reuse in future.