docs: def checktext(sometext, interchange = ALL):
  	"""
  		Checks that some text is palindrome. Checking performs case-insensitive
  		
  		:param str sometext:
  		    It is some string that will be checked for palindrome as text.
  			
  		    What is the text see at help(palindromus.istext)
  			
  		    The text can be multiline.
  			
  		:keyword dict interchange:
  		    It is dictionary of interchangeable letters
  			
  		:except TypeError:
  		    If the checked text is not a string
  			
  		:return bool:
  	"""
  	# check invalid data types
  	OnlyStringsCanBeChecked(sometext)
  	
  	if istext(sometext):
  		return checkstring(sometext, interchange = interchange)
  	else:
  		return False