'Evaluate a PEP 426 environment marker on CPython 2.4+.
Return a boolean indicating the marker result in this environment.
Raise SyntaxError if marker is invalid.
This implementation uses the \'parser\' module, which is not implemented
on
Jython and has been superseded by the \'ast\' module in Python 2.6 and
later.'

@classmethod
def evaluate_marker(cls, text, extra=None):

    return cls.interpret(parser.expr(text).totuple(1)[1])
