>>> from mechanize import Request
>>> Request("http://example.com/foo#frag").get_selector()
'/foo'

>>> Request("http://example.com?query").get_selector()
'/?query'

>>> Request("http://example.com").get_selector()
'/'


Request Headers Dictionary
--------------------------

The Request.headers dictionary is not a documented interface.  It should
stay that way, because the complete set of headers are only accessible
through the .get_header(), .has_header(), .header_items() interface.
However, .headers pre-dates those methods, and so real code will be using
the dictionary.

The introduction in 2.4 of those methods was a mistake for the same reason:
code that previously saw all (urllib2 user)-provided headers in .headers
now sees only a subset (and the function interface is ugly and incomplete).
A better change would have been to replace .headers dict with a dict
subclass (or UserDict.DictMixin instance?)  that preserved the .headers
interface and also provided access to the "unredirected" headers.  It's
probably too late to fix that, though.


Check case normalization:

>>> url = "http://example.com"
>>> Request(url, headers={"Spam-eggs": "blah"}).headers["Spam-Eggs"]
'blah'
>>> Request(url, headers={"spam-EggS": "blah"}).headers["Spam-Eggs"]
'blah'

Currently, Request(url, "Spam-eggs").headers["Spam-eggs"] raises KeyError,
but that could be changed in future.


Request Headers Methods
-----------------------

Note the case normalization of header names here, to .capitalize()-case.
This should be preserved for backwards-compatibility.  (In the HTTP case,
normalization to .title()-case is done by urllib2 before sending headers to
httplib).

>>> url = "http://example.com"
>>> r = Request(url, headers={"Spam-eggs": "blah"})
>>> r.has_header("Spam-eggs")
True
>>> r.header_items()
[('Spam-Eggs', 'blah')]
>>> r.add_header("Foo-Bar", "baz")
>>> items = r.header_items()
>>> items.sort()
>>> items
[('Foo-Bar', 'baz'), ('Spam-Eggs', 'blah')]
>>> r.has_header("Not-there")
False
>>> print(r.get_header("Not-there"))
None
>>> r.get_header("Not-there", "default")
'default'


Header Order
-------------
