old_contents: # SNMP agent backend e.g. Agent access to Managed Objects
  from pysnmp.smi import builder, instrum, exval
  
  print 'Loading MIB modules...',
  mibBuilder = builder.MibBuilder().loadModules(
      'SNMPv2-MIB', 'SNMP-FRAMEWORK-MIB', 'SNMP-COMMUNITY-MIB'
      )
  print 'done'
  
  print 'Building MIB tree...',
  mibInstrum = instrum.MibInstrumController(mibBuilder)
  print 'done'
  
  print 'Remote manager write/create access to MIB instrumentation: ',
  print mibInstrum.writeVars(
      (((1,3,6,1,6,3,18,1,1,1,1,109,121,110,109,115), 'mynms'),
       ((1,3,6,1,6,3,18,1,1,1,2,109,121,110,109,115), 'mycomm'),
       ((1,3,6,1,6,3,18,1,1,1,3,109,121,110,109,115), 'mynmsname'),
       ((1,3,6,1,6,3,18,1,1,1,7,109,121,110,109,115), 'volatile'))
      )
  
  print 'Remote manager read access to MIB instrumentation (table walk)'
  oid, val = (), None
  while 1:
      oid, val = mibInstrum.readNextVars(((oid, val),))[0]
      if exval.endOfMib.isSameTypeWith(val):
          break
      print oid, val
  
new_contents: # SNMP agent backend e.g. Agent access to Managed Objects
  from pysnmp.smi import builder, instrum, exval
  
  print 'Loading MIB modules...',
  mibBuilder = builder.MibBuilder().loadModules(
      'SNMPv2-MIB', 'SNMP-FRAMEWORK-MIB', 'SNMP-COMMUNITY-MIB'
      )
  print 'done'
  
  print 'Building MIB tree...',
  mibInstrum = instrum.MibInstrumController(mibBuilder)
  print 'done'
  
  print 'Remote manager write/create access to MIB instrumentation: ',
  print mibInstrum.writeVars(
      (((1,3,6,1,6,3,18,1,1,1,1,109,121,110,109,115), 'mynms'),
       ((1,3,6,1,6,3,18,1,1,1,2,109,121,110,109,115), 'mycomm'),
       ((1,3,6,1,6,3,18,1,1,1,3,109,121,110,109,115), 'mynmsname'),
       ((1,3,6,1,6,3,18,1,1,1,7,109,121,110,109,115), 'volatile'))
      )
  
  print 'Remote manager read access to MIB instrumentation (table walk)'
  oid, val = (), None
  while 1:
      oid, val = mibInstrum.readNextVars(((oid, val),))[0]
      if exval.endOfMib.isSameTypeWith(val):
          break
      print oid, val
  
  print 'Unloading MIB modules...',
  mibBuilder.unloadModules(
      'SNMPv2-MIB', 'SNMP-FRAMEWORK-MIB', 'SNMP-COMMUNITY-MIB'
      )
  print 'done'
  
subject: make use of mibBuilder.unloadModules()