def warning(self, message, print_location=True):
        """Displays warning message. Uses exshared for current location of parsing"""
        msg = "Warning"
        if print_location and (exshared.location != None):
            wline = lineno(exshared.location, exshared.text)
            wcol = col(exshared.location, exshared.text)
            wtext = line(exshared.location, exshared.text)
            msg += " at line %d, col %d" % (wline, wcol)
        msg += ": %s" % message
        if print_location and (exshared.location != None):
            msg += "\n%s" % wtext
        print(msg)
Displays warning message. Uses exshared for current location of parsing