Abaqus - The Abaqus python script to find out an instance name by its cutting surface name

hi, I want to use a surface name to get an instance name which attached this surface by Abaqus python script. For example, set the pre-load for a bolt, the section surface is required. 

a = mdb.models['model-1'].rootAssembly
region = a.surfaces['Surf-14']
datumAxis = mdb.models['bolt-load'].rootAssembly.instances['bolt-1'].datums[1]
mdb.models['model-1'].BoltLoad(name='Boltload', 
createStepName='Boltload-step', region=region, magnitude=4000.0, 
boltMethod=APPLY_FORCE, datumAxis=datumAxis)

How to find out the instance ['bolt-1'] by the cutting surface ['Surf-14'] ?

Who can tell me how to write the script for this question?