def accept_invitation(self, invitation):
assert isinstance(invitation, github.Invitation.Invitation) or isinstance(invitation, int)<EOL>if isinstance(invitation, github.Invitation.Invitation):<EOL><INDENT>invitation = invitation.id<EOL><DEDENT>headers, data = self._requester.requestJsonAndCheck(<EOL>"<STR_LIT>",<EOL>"<STR_LIT>" + str(invitation),<EOL>input={}<EOL>)<EOL>
:calls: `PATCH /user/repository_invitations/:invitation_id <https://developer.github.com/v3/repos/invitations/>`
:param invitation: :class:`github.Invitation.Invitation` or int
:rtype: None