import xml.etree.ElementTree as et
def check_elem (elem, target, field = None):
	"""Return True if target string found in element children's text attr"""
	if hasattr(elem, "text"):
		if target in str(elem.text).lower():
			if not field:
				return True
			else:
				if field in elem.tag.lower():
					return True
				else:
					print ("close, but no")
		else:
			if len (elem)>0:
				for child in elem:
					x = check_elem(child, target, field=field)
					if x:
						return True
	
def check_descr (fname, target, field = None):
	"""Returns True if target string found in description texts of fb2 file\
	else returns False
	fname - file name
	target - string to find
	field - field name (element.tag), default None (all tags)"""
	tree = et.parse(fname)
	root = tree.getroot()
	#root[0] - description , root[1] - body
	target = target.lower()
	if field:
		field = field.lower()
	if len(root[0])>0:
		print ("Checking description for \'{}\'".format(target))
		for thing in root[0]:
			x=check_elem(thing, target=target, field=field)
			if x:
				return True
	elif len(root[1])>0:
		for thing in root[1]:
			if "annotation" in thing.tag or "title" in thing.tag:
				print ("Checking annotation for \'{}\'".format(target))
				for thing1 in thing:
					x=check_elem(elem=thing1, target=target, field=field)
					if x:
						return True
	else:
		return False

>>> import xml.etree.ElementTree as et
>>> 
>>> doc = et.fromstring('<x/>')
>>> hasattr(doc, 'text')
True
>>>

>>> import xml.etree.ElementTree as et
>>> 
>>> doc = et.fromstring('<x>abc</x>')
>>> doc.text
'abc'
>>> type(doc.text)
<class 'str'>
>>>

>>> import xml.etree.ElementTree as et
>>> 
>>> doc = et.fromstring('<x>abc<y>def1</y><y>def2</y></x>')
>>> 
>>> lst = doc.findall('y')
>>> lst
[<Element 'y' at 0xb73f33c4>, <Element 'y' at 0xb73f3414>]
>>> [i.text for i in lst]
['def1', 'def2']
>>>

In [1]: import xml.etree.ElementTree as et
In [2]: doc1 = et.fromstring("<x>abc</x>")
In [3]: doc1.text
Out[3]: 'abc'
In [4]: doc2 = et.fromstring("<z>AbC</z>")
In [5]: doc2.text
Out[5]: 'AbC'
In [6]: doc2.text == doc1.text
Out[6]: False
In [7]: doc2.text.lower() == doc1.text
Out[7]: True

if elem.text is not None: