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 delete(self, dn, controls=None):

        self.result = { 'dn' : '',
                        'referrals' : None,
                        'description' : 'success',
                        'result' : 0,
                        'message' : '',
                        'type' : 'addResponse'}

        # Check to see if the user exists in the directory
        try:
            index = self._find_user(dn)
        except StopIteration:
            # If we get here the user doesn't exist so continue
            self.result["description"] = "failure"
            self.result["result"] = 32
            self.result["message"] = "Error no such object: {0}".format(dn)
            return False

        # Delete the entry object for the user
        self.directory.pop(index)

        # Attempt to write changes to disk
        with open(DIRECTORY, 'w+') as f:
            f.write(str(self.directory))

        return True