code: def update_style(title,defaults=None,mappings=None,host=cytoscape_host,port=cytoscape_port,verbose=False):
      
  
      if defaults: 
          defaults_=[]    
          for d in defaults:
              if d:
                  defaults_.append(d)
          defaults=defaults_
  
      if mappings:
          mappings_=[]
          for m in mappings:
              if m:
                  mappings_.append(m)
          mappings=mappings_
  
  
      URL="http://"+str(host)+":"+str(port)+"/v1/styles/"+str(title)
      if verbose:
          print(URL)
          sys.stdout.flush()
  
      response = urllib2.urlopen(URL)    
      response = response.read()
      response = json.loads(response)
      
      olddefaults=response["defaults"]
      oldmappings=response["mappings"]
  
      if mappings:
          mappings_visual_properties=[ m["visualProperty"] for m in mappings ]
          newmappings=[ m for m in oldmappings if m["visualProperty"] not in mappings_visual_properties ]
          for m in mappings:
              newmappings.append(m)
      else:
          newmappings=oldmappings
  
      if defaults:
          defaults_visual_properties=[ m["visualProperty"] for m in defaults ]
          newdefaults=[ m for m in olddefaults if m["visualProperty"] not in defaults_visual_properties ]
          for m in defaults:
              newdefaults.append(m)
      else:
          newdefaults=olddefaults
          
      r=requests.delete(URL)
      CheckResponse(r)    
  
      URL="http://"+str(host)+":"+str(port)+"/v1/styles"
      PARAMS={"title":title,\
             "defaults":newdefaults,\
             "mappings":newmappings}
      r = requests.post(url = URL, json = PARAMS)
      CheckResponse(r)
docs: Updates a visual style
      
      :param title: title of the visual style
      :param defaults: a list of dictionaries for each visualProperty
      :param mappings: a list of dictionaries for each visualProperty
      :param host: cytoscape host address, default=cytoscape_host
      :param port: cytoscape port, default=1234
      
      :retunrs: nothing