'Import library with optionally lxml mode enabled.
By default this library uses Python\'s standard
[https://docs.python.org/2/library/xml.etree.elementtree.html|ElementTree]
module for parsing XML. If ``use_lxml`` argument is given a true value
(see `Boolean arguments`), the library will use [http://lxml.de|lxml]
module instead. See `Using lxml` section for benefits provided by lxml.
Using lxml requires that the lxml module is installed on the system.
If lxml mode is enabled but the module is not installed, this library
will emit a warning and revert back to using the standard ElementTree.
The support for lxml is new in Robot Framework 2.8.5.'

def __init__(self, use_lxml=False):

    use_lxml = is_truthy(use_lxml)
    if (use_lxml and lxml_etree):
        self.etree = lxml_etree
        self.modern_etree = True
        self.lxml_etree = True
    else:
        self.etree = ET
        self.modern_etree = (ET.VERSION >= '1.3')
        self.lxml_etree = False
    if (use_lxml and (not lxml_etree)):
        logger.warn('XML    library    reverted    to    use    standard    ElementTree    because    lxml    module    is    not    installed.')
    self._ns_stripper = NameSpaceStripper(self.etree, self.lxml_etree)
