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:

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