def add(self, elem, replace=False):
        """Add a requirement.

        :param elem: a string or :class:`Requirement` instance.
        :param replace: if `True`, packages in the set with the same name will
            be removed first.
        """
        if isinstance(elem, text_type):
            elem = Requirement.coerce(elem)
        if replace and elem in self:
            self.remove(elem)
        super(Requirements, self).add(elem)
def get(self, section, option):
            if _section == section:
                if option == 'memcache_servers':
                    if _srvs == 'error':
                        raise NoOptionError(option, section)
                    return _srvs
                elif option == 'memcache_serialization_support':
                    if _sers == 'error':
                        raise NoOptionError(option, section)
                    return _sers
                elif option in ('memcache_max_connections',
                                'max_connections'):
                    if _maxc == 'error':
                        raise NoOptionError(option, section)
                    return _maxc
                else:
                    raise NoOptionError(option, section)
            else:
                raise NoSectionError(option)