def remove(self, elem):
        """Remove a requirement.

        :param elem: a string or :class:`Requirement` instance.
        """
        if isinstance(elem, text_type):
            for requirement in self:
                if requirement.package == elem:
                    return super(Requirements, self).remove(requirement)
        return super(Requirements, self).remove(elem)
def _getQUICHeader(self, count):
        if type(count) is not hex:
            try:
                count_id = chr(count)
            except:
                sys.stderr.write("Count must be int or hex.\n")
                return 1
        else:
            count_id = count

        if count > self.max_packets:
            sys.stderr.write("[-]\tCount must be maximum of 255.\n")
            return 1

        header = "\x0c"                     # Public Flags
        header += self.sequence             # Adding CID
        header += count_id                  # Packet Count
        return header