'Initializes a CountableResource.
Countable resources are those resources which directly
correspond to objects in the database, i.e., volumes, gigabytes,
etc., but for which a count by project ID is inappropriate.  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.
Note that this counting is not performed in a transaction-safe
manner.  This resource class is a temporary measure to provide
required functionality, until a better approach to solving
this problem can be evolved.
:param name: The name of the resource, i.e., "volumes".
: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.'

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

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