def coerce(cls, string):
        """Create a :class:`Requirement` object from a given package spec."""
        match = re.match(cls.spec_regex, string)
        if not match:
            raise InvalidRequirementSpecError("could not parse requirement")
        package = match.group(1)
        if all(match.group(2, 3)):
            version = "".join(match.group(2, 3))
        else:
            version = None
        return cls(package, version)
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)