How to use the elementpath.XPath1Parser.symbol_table function in elementpath

from .namespaces import get_namespace
from .etree import ElementTree, PyElementTree, SafeXMLParser, etree_tostring, etree_iter_location_hints


DEFUSE_MODES = ('always', 'remote', 'never')


XML_RESOURCE_XPATH_SYMBOLS = {
    'position', 'last', 'not', 'and', 'or', '!=', '<=', '>=', '(', ')', 'text',
    '[', ']', '.', ',', '/', '|', '*', '=', '<', '>', ':', '(end)', '(name)',
    '(string)', '(float)', '(decimal)', '(integer)'
}


class XmlResourceXPathParser(XPath1Parser):
    symbol_table = {k: v for k, v in XPath1Parser.symbol_table.items() if k in XML_RESOURCE_XPATH_SYMBOLS}
    SYMBOLS = XML_RESOURCE_XPATH_SYMBOLS


XmlResourceXPathParser.build_tokenizer()


def is_remote_url(url):
    return isinstance(url, string_base_type) and urlsplit(url).scheme not in ('', 'file')


def url_path_is_directory(url):
    return os.path.isdir(urlsplit(url).path)


def url_path_is_file(url):
    return os.path.isfile(urlsplit(url).path)

from .exceptions import XMLSchemaValidationError
from .xsdbase import XsdComponent

XSD_IDENTITY_XPATH_SYMBOLS = {
    'processing-instruction', 'following-sibling', 'preceding-sibling',
    'ancestor-or-self', 'attribute', 'following', 'namespace', 'preceding',
    'ancestor', 'position', 'comment', 'parent', 'child', 'false', 'text', 'node',
    'true', 'last', 'not', 'and', 'mod', 'div', 'or', '..', '//', '!=', '<=', '>=', '(', ')',
    '[', ']', '.', '@', ',', '/', '|', '*', '-', '=', '+', '<', '>', ':', '(end)', '(name)',
    '(string)', '(float)', '(decimal)', '(integer)', '::'
}


class XsdIdentityXPathParser(XPath1Parser):
    symbol_table = {k: v for k, v in XPath1Parser.symbol_table.items() if k in XSD_IDENTITY_XPATH_SYMBOLS}
    SYMBOLS = XSD_IDENTITY_XPATH_SYMBOLS


XsdIdentityXPathParser.build_tokenizer()


class XsdSelector(XsdComponent):
    """Class for defining an XPath selector for an XSD identity constraint."""
    _ADMITTED_TAGS = {XSD_SELECTOR}
    pattern = re.compile(get_python_regex(
        r"(\.//)?(((child::)?((\i\c*:)?(\i\c*|\*)))|\.)(/(((child::)?((\i\c*:)?(\i\c*|\*)))|\.))*(\|"
        r"(\.//)?(((child::)?((\i\c*:)?(\i\c*|\*)))|\.)(/(((child::)?((\i\c*:)?(\i\c*|\*)))|\.))*)*"
    ))

    def __init__(self, elem, schema, parent):
        super(XsdSelector, self).__init__(elem, schema, parent)