'Initializes a CountableResource.
Countable resources are those resources which directly
correspond to objects in the database, i.e., network, subnet,
etc.,.  A CountableResource must be constructed with a counting
function, which will be called to determine the current counts
of the resource.
The counting function will be passed the context, along with
the extra positional and keyword arguments that are passed to
Quota.count().  It should return an integer specifying the
count.
:param name: The name of the resource, i.e., "instances".
:param count: A callable which returns the count of the
resource. The arguments passed are as described
above.
:param flag: The name of the flag or configuration option
which specifies the default value of the quota
for this resource.
:param plural_name: Plural form of the resource name. If not
specified, it is generated automatically by
appending an \'s\' to the resource name, unless
it ends with a \'y\'. In that case the last
letter is removed, and \'ies\' is appended.
Dashes are always converted to underscores.'

def __init__(self, name, count, flag=None, plural_name=None):

    super(CountableResource, self).__init__(name, flag=flag, plural_name=plural_name)
    self._count_func = count
