How to use the sdv.errors.ValidationError function in sdv

"""

    rdict = {'xml': None,
             'best_practices': None,
            #'profile': None,
             }
    xml = xml.encode('utf-8').strip()
    f = BytesIO(xml)
    try:
        result = sdv.validate_xml(f, schemaloc=True)
        rdict['xml'] = result.as_dict()
    except sdv.errors.UnknownSTIXVersionError, e:
        rdict['xml'] = "Could not determine @version attribute: %s" % str(e)
    except sdv.errors.InvalidSTIXVersionError, e:
        rdict['xml'] = "@version attribute is invalid: %s" % str(e)
    except sdv.errors.ValidationError, e:
        rdict['xml'] = "Schema directory not found or schemaloc is False: %s" % str(e)
    except sdv.errors.XMLSchemaImportError, e:
        rdict['xml'] = "Error while processing schemas for validation: %s" % str(e)
    except sdv.errors.XMLSchemaIncludeError, e:
        rdict['xml'] = "Error processing xs:include directives: %s" % str(e)
    except IOError, e:
        rdict['xml'] = "Not a valid XML document: %s" % str(e)
    except Exception, e:
        rdict['xml'] = str(e)

    f.seek(0)
    try:
        result = sdv.validate_best_practices(f)
        rdict['best_practices'] = result.as_dict()
    except sdv.errors.UnknownSTIXVersionError, e:
        rdict['best_practices'] = "Could not determine @version attribute: %s" % str(e)

# Copyright (c) 2014, The MITRE Corporation. All rights reserved.
# See LICENSE.txt for complete terms.


class ValidationError(Exception):
    """Base Exception for all validator-specific exceptions. This is used
    directly by some modules as a generic Exception.

    """
    pass


class UnknownNamespaceError(ValidationError):
    """Raised when an unknown namespace is encountered in a function.

    """
    pass


class UnknownVocabularyError(ValidationError):
    """Raised when an unknown controlled vocabulary name is discovered
    during best practice validation.

    """
    pass


class IdrefLookupError(ValidationError):
    """Raised when an attempt to resolve an ID reference fails. This can

class ValidationError(Exception):
    """Base Exception for all validator-specific exceptions. This is used
    directly by some modules as a generic Exception.

    """
    pass


class UnknownNamespaceError(ValidationError):
    """Raised when an unknown namespace is encountered in a function.

    """
    pass


class UnknownVocabularyError(ValidationError):
    """Raised when an unknown controlled vocabulary name is discovered
    during best practice validation.

    """
    pass


class IdrefLookupError(ValidationError):
    """Raised when an attempt to resolve an ID reference fails. This can
    occur when the full STIX component definition resides outside of the
    input document.

    """
    def __init__(self, idref, message=None):
        super(IdrefLookupError, self).__init__(message)
        self.idref = idref

def check_root(doc):
    if utils.is_stix(doc):
        return

    error = "Input document does not contain a valid STIX root element."
    raise errors.ValidationError(error)

"""
    def __init__(self, idref, message=None):
        super(IdrefLookupError, self).__init__(message)
        self.idref = idref


class XMLSchemaIncludeError(ValidationError):
    """Raised when errors occur during the processing of ``xs:include``
    directives found within schema documents.

    """
    pass


class XMLSchemaImportError(ValidationError):
    """Raised when errors occur when generating ``xs:import`` directives for
    the "uber" schema, used to validate XML instance documents.

    """
    pass


class UnknownSTIXVersionError(ValidationError):
    """Raised when no STIX version information can be found in an instance
    document and no version information was provided to a method which
    requires version information.

    """
    pass

the "uber" schema, used to validate XML instance documents.

    """
    pass


class UnknownSTIXVersionError(ValidationError):
    """Raised when no STIX version information can be found in an instance
    document and no version information was provided to a method which
    requires version information.

    """
    pass


class InvalidSTIXVersionError(ValidationError):
    """Raised when an invalid version of STIX is discovered within an instance
    document or is passed into a method which depends on STIX version
    information.

    Args:
        message: The error message.
        expected: A version or list of expected versions.
        found: The STIX version that was declared for an instance document or
            found within an instance document.

    """
    def __init__(self, message, expected=None, found=None):
        super(InvalidSTIXVersionError, self).__init__(message)
        self.expected = expected
        self.found = found

information.

    Args:
        message: The error message.
        expected: A version or list of expected versions.
        found: The CybOX version that was declared for an instance document or
            found within an instance document.

    """
    def __init__(self, message, expected=None, found=None):
        super(InvalidCyboxVersionError, self).__init__(message)
        self.expected = expected
        self.found = found


class ProfileParseError(ValidationError):
    """Raised when an error occurs during the parse or initialization
    of a STIX profile document.

    """
    pass

"""
    try:
        if isinstance(doc, etree._Element):  # noqa
            root = doc
        elif isinstance(doc, etree._ElementTree):  # noqa
            root = doc.getroot()
        else:
            parser = get_xml_parser()
            if isinstance(doc, StringIO):
                tree = etree.parse(BytesIO(doc.getvalue().encode()), parser=parser)
            else:
                tree = etree.parse(doc, parser=parser)
            root = tree.getroot()
    except Exception as ex:
        raise errors.ValidationError(str(ex))

    return root