flowFile = session.get() 
if (flowFile != None):
    # All processing code starts at this indent
# implicit return at the end

flowFileList = session.get(100)
if not flowFileList.isEmpty():
    for flowFile in flowFileList: 
         # Process each FlowFile here

flowFile = session.create() 
# Additional processing here

flowFile = session.get() 
if (flowFile != None):
    newFlowFile = session.create(flowFile) 
    # Additional processing here

flowFile = session.get() 
if (flowFile != None):
    flowFile = session.putAttribute(flowFile, 'myAttr', 'myValue')
# implicit return at the end

attrMap = {'myAttr1':'1', 'myAttr2':str(2)}
flowFile = session.get() 
if (flowFile != None):
    flowFile = session.putAllAttributes(flowFile, attrMap)
# implicit return at the end

flowFile = session.get() 
if (flowFile != None):
    myAttr = flowFile.getAttribute('filename')
# implicit return at the end

flowFile = session.get() 
if (flowFile != None):
    for key,value in flowFile.getAttributes().iteritems():
       # Do something with key and/or value
# implicit return at the end

flowFile = session.get() 
if (flowFile != None):
    # All processing code starts at this indent
    if errorOccurred:
        session.transfer(flowFile, REL_FAILURE)
    else:
        session.transfer(flowFile, REL_SUCCESS)
# implicit return at the end

from java.lang import Object
from jarray import array
objArray = ['Hello',1,True]
javaArray = array(objArray, Object)
log.info('Found these things: {} {} {}', javaArray)

from org.apache.commons.io import IOUtils
from java.nio.charset import StandardCharsets
from org.apache.nifi.processor.io import InputStreamCallback
 
# Define a subclass of InputStreamCallback for use in session.read()
class PyInputStreamCallback(InputStreamCallback):

    def __init__(self):
    
        pass
    def process(self, inputStream):
        text = IOUtils.toString(inputStream, StandardCharsets.UTF_8)
    # Do something with text here
# end class

flowFile = session.get()
if(flowFile != None):
    session.read(flowFile, PyInputStreamCallback())
# implicit return at the end

from org.apache.commons.io import IOUtils
from java.nio.charset import StandardCharsets
from org.apache.nifi.processor.io import OutputStreamCallback
 
# Define a subclass of OutputStreamCallback for use in session.write()
class PyOutputStreamCallback(OutputStreamCallback):

    def __init__(self):
        pass
        
    def process(self, outputStream):
        outputStream.write(bytearray('Hello World!'.encode('utf-8')))
# end class

flowFile = session.get()
if(flowFile != None):
    flowFile = session.write(flowFile, PyOutputStreamCallback())
# implicit return at the end

from org.apache.commons.io import IOUtils
from java.nio.charset import StandardCharsets
from org.apache.nifi.processor.io import StreamCallback
 
# Define a subclass of StreamCallback for use in session.write()
class PyStreamCallback(StreamCallback):

  def __init__(self):
        pass
        
  def process(self, inputStream, outputStream):
    text = IOUtils.toString(inputStream, StandardCharsets.UTF_8)
    outputStream.write(bytearray('Hello World!'[::-1].encode('utf-8')))
# end class

flowFile = session.get()
if(flowFile != None):
    flowFile = session.write(flowFile, PyStreamCallback())
# implicit return at the en

flowFile = session.get()
if(flowFile != None):
    try:
        # Something that might throw an exception here
        # Last operation is transfer to success (failures handled in the catch block)
        session.transfer(flowFile, REL_SUCCESS)
    except:
        log.error('Something went wrong', e)
        session.transfer(flowFile, REL_FAILURE)
# implicit return at the end