need help in Naive bayes classifier code

hello everybody !

i need a good programmer helping me because i found an open source code but i still have an error and i have been tried since 2 week ago ..

this part of code :

usage = ('Usage: %s <file> <expected doctype> <other doctype>' % sys.argv[0])


if len(sys.argv) !=4:
		raise ValueError(usage)

input_file = sys.argv[1]
doctype_expected = sys.argv[2]
doctype_other = sys.argv[3]

classifier.set_doctypes(doctype_expected, doctype_other)

results = None 

what is <file> mean is it a database or what ?
i hope any one explane the usage variables content for me />