#python 3.6
#蔡军生 
#http://blog.csdn.net/caimouse/article/details/51749579
#
import re
twitter = re.compile(
  '''
  # A twitter handle: @username
  (?<=@)
  ([\w\d_]+)    # username
  ''',
  re.VERBOSE)
text = '''This text includes two Twitter handles.
One for @caimouse, and one for the author, @caijunsheng.
'''
print(text)
for match in twitter.findall(text):
  print('Handle:', match)

 This text includes two Twitter handles.
One for @caimouse, and one for the author, @caijunsheng.
Handle: caimouse
Handle: caijunsheng