Check whether the character is a tone or word accent symbol. In strict mode
	return True only for the symbols listed in the last group of the chart. If
	strict=False, also accept symbols that belong to the Modifier Tone Letters
	Unicode block [1].

	[1]: http://www.unicode.org/charts/PDF/UA700.pdf

def is_tone(char, strict=True):
	"""
	Check whether the character is a tone or word accent symbol. In strict mode
	return True only for the symbols listed in the last group of the chart. If
	strict=False, also accept symbols that belong to the Modifier Tone Letters
	Unicode block [1].

	[1]: http://www.unicode.org/charts/PDF/UA700.pdf
	"""
	if char in chart.tones:
		return True

	if not strict:
		return 0xA700 <= ord(char) <= 0xA71F

	return False