code: def add_uid(self, uid, selfsign=True, **prefs):
          
          uid._parent = self
          if selfsign:
              uid |= self.certify(uid, SignatureType.Positive_Cert, **prefs)
  
          self |= uid
docs: Add a User ID to this key.
  
          :param uid: The user id to add
          :type uid: :py:obj:`~pgpy.PGPUID`
          :param selfsign: Whether or not to self-sign the user id before adding it
          :type selfsign: ``bool``
  
          Valid optional keyword arguments are identical to those of self-signatures for :py:meth:`PGPKey.certify`.
          Any such keyword arguments are ignored if selfsign is ``False``