def is_abbr(word):
	"""return True if word is abbr, False otherwise"""
	# more then 2 chars in word are uppercase 
	num_of_uppers = sum(map(str.isupper, word))
	num_of_lowers = sum(map(str.islower, word))
	if num_of_uppers >= 2 and (num_of_uppers / len(word) >= 0.5):
		return True