def to_bikel_format(tagged_sents):
	"""
	Converts to bikel format (bracketing). Takes multiple sentences where each
	sentence is a list of (word, tag) tuples.
	
	Parameters:: tagged_sents (list(list(tuple(str, str))))
	Return type:: (str)
	"""
	result = ""
	for sentence in tagged_sents:
		result += "("
		for item in sentence:
			result = result + "("+item[0]+" "+"("+item[1]+")) "
		result += ") "
	return result