from string import split, join

def chomp(line):
	""" get rid of a trailling newline """
	try:
		if line[-1] == '\n':
			line = line[:-1]
	except IndexError:
		pass
	return line

class reader:
	""" read tsv from a file """
	def __init__(self, file):
		self.file = file
	def read(self):
		line = self.file.readline()
		if not line:
			return None
		line = chomp(line)
		values = split(line, "\t")
		# note - no escaping of \n \t yet
		return values

class writer:
	""" write tsv to a file """
	def __init__(self, file):
		self.file = file
	def write(self, values):
		if values == None:
			self.file.close()
			return
		# note - no escaping of \n \t yet
		line = join(values, "\t")
		line = line + "\n"
		self.file.write(line)