this crawler is to collect papers from arxiv and conference.
for different conference, keyword and time range, please modify following variable
conferences = ['www'] # conference shortcut on dblp
context_key = set(['change']) # keyword in title
arthur_key = set(['Kuo Yu Huang']) # arthur's full name
months = ['{:0>2d}'.format(i+1) for i in range(12)] # month for arxiv
years = ['{:0>2d}'.format(i) for i in range(17, 20)] # year for conference and arxiv
fields = ['CL'] # category shortcut on arxiv