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    latitude and longitude recorded in the photo.

    Moving right along, whether or not we've just updated FireEagle the
    service is queried for your current location (again).

    Once the hierarchy has been retrieved, the next step is to try and
    retrieve a "context" node. Whereas when testing GPS information the
    "best guess" node is assumed this is not necessarily the case when
    trying to use FireEagle to add tags.

    The context node is determined by comparing the photo's date against the
    *located-at* (or date recorded) attribute for specific items in the
    FireEagle hierarchy. Since most cameras still don't record GPS
    information it is necessary to do some work to gues^H^H^H I mean infer
    how "close" you are to the last recorded location.

    For example, if it's been more than a couple of hours since you last
    updated FireEagle you might still be in the same neighbourhood but if
    it's been more than half a day chances are good that you're been on the
    move but are still in the same city.

    (It goes without saying that there are lots of edge cases some of which
    will try to be addressed in the as-yet unwritten
    Flickr::Upload::FireDopplr.)

    The following tests are applied :

    * First a "best guess" location is queried
        If it is present and its *located-at* date is less than or equal to
        an hour, it is the context node.

        An alternate value may be set by passing a *offset_fireeagle_exact*
        argument, measured in seconds, to the *upload* method.

    * Next a location of type "neighborhood" is queried
        If it is present and its *located-at* date is less than or equal to
        two hours, it is the context node.

        An alternate value may be set by passing a
        *offset_fireeagle_neighbourhood* (or neighborhood) argument,
        measured in seconds, to the *upload* method.

    * Next a location of type "locality" is queried
        If it is present and its *located-at* date is less than or equal to
        twelve hours, it is the context node.

        An alternate value may be set by passing a
        *offset_fireeagle_locality* argument, measured in seconds, to the
        *upload* method.

    * If none of those tests pass then...
        ...there is no context node.

    Assuming that a context node has been identified *and* there is GPS
    information stored in the photo, the *flickr.places.findByLatLon* method
    is called (passing the photo's latitude and longitude) to ensure that
    the (Flickr) places IDs for both the response and the context node
    match.

    If they *don't* match then the context node is destroyed and the
    following tags are added : places:PLACETYPE=PLACEID; woe:id=WOEID; the
    name of the location (formatted according to the object's "tagify"
    rules).

    On the other hand, if the context node is still around, after all that,
    then it is used to add tags.

    At a minimum a fireeagle:id=CONTEXTNODEID tag is added. If the place
    type for the context node is equal to or more precise than a
    neighbourhood, the neighbourhood's name is added as a tag. If the place
    type for the context node is equal to or more precise than a locality,
    the locality's name is added as a tag as well as fireeagle:id=ID,
    places:locality=PLACEID and woe:id=WOEID tags.

    We're almost done : Assuming a context node and no GPS information in
    the photo, the nodes latitude and longitude are calculated to use as
    arguments when calling the *flickr.photos.geo.setLocation* method.

    The coordinates are "calculated" because not every location in the
    FireEagle hierarchy has a centroid. If no centroid is present then the
    node's bounding box is used and the centroid is assumed to be the center
    of the box. The photo's "accuracy" (in Flickr terms) is determined
    according to the node's place type.

    Finally, the photo is uploaded (and geotagged if necessary).

    No really.

ERROR HANDLING
    Flickr::Upload::FireEagle subclasses Error.pm to catch and throw
    exceptions. Although this is still a mostly un-Perl-ish way of doing
    things, it seemed like the most sensible way to handle the variety of
    error cases. I don't love it but we'll see.

    This means that the library will throw fatal exceptions and you will
    need to code around it using either *eval* or - even better - *try* and
    *catch* blocks.

    There are four package specific exception handlers :

    * FUFEException
        An error condition specific to *Flickr::Upload::FireEagle* was
        triggered.

    * FlickrUploadException
        An error condition specific to *Flickr::Upload* was triggered.

    * FlickrAPIException
        An error condition specific to calling the Flickr API (read :
        *Flickr::API*) was triggered.

        This is the only exception handler that defines its own additional
        methods. They are :

        * error_code
            The numeric error code returned by the Flickr API.

        * error_message
            The textual error message returned by the Flickr API.

    * NetFireEagleException