code: def is_letter(char, strict=True):
  	
  	if (char in chart.consonants) or (char in chart.vowels):
  		return True
  
  	if not strict:
  		return unicodedata.category(char) in ['Ll', 'Lo', 'Lt', 'Lu']
  
  	return False
docs: Check whether the character is a letter (as opposed to a diacritic or
  	suprasegmental).
  
  	In strict mode return True only if the letter is part of the IPA spec.