'Return list of sizes on a provider.
@inherits: :class:`NodeDriver.list_sizes`
:return: List of compute node sizes supported by the cloud provider.
:rtype:  ``list`` of :class:`OpenNebulaNodeSize`'

def list_sizes(self, location=None):

    return [OpenNebulaNodeSize(id=1, name='small', ram=1024, cpu=1, disk=None, bandwidth=None, price=None, driver=self), OpenNebulaNodeSize(id=2, name='medium', ram=4096, cpu=4, disk=None, bandwidth=None, price=None, driver=self), OpenNebulaNodeSize(id=3, name='large', ram=8192, cpu=8, disk=None, bandwidth=None, price=None, driver=self), OpenNebulaNodeSize(id=4, name='custom', ram=0, cpu=0, disk=None, bandwidth=None, price=None, driver=self)]
