'Return the original bottom-level bound segment dictionary.
This property returns the original bottom-level bound segment
dictionary, or None if the port was previously unbound. For a
previously bound port, original_bottom_bound_segment is
equivalent to original_binding_levels[-1][BOUND_SEGMENT], and
returns the segment whose binding supplied the port\'s previous
binding:vif_type and binding:vif_details attribute values.
This property is only valid within calls to
update_port_precommit and update_port_postcommit. It returns
None otherwise.'

@abc.abstractproperty
def original_bottom_bound_segment(self):

    pass
