def remove(self, elem):
        """Remove a requirement.

        :param elem: a string or :class:`Requirement` instance.
        """
        if isinstance(elem, text_type):
            for requirement in self:
                if requirement.package == elem:
                    return super(Requirements, self).remove(requirement)
        return super(Requirements, self).remove(elem)
def __init__(self, parent, window):
		self._parent = parent
		self._window = window
		self._application = self._parent._application

		# create user interface
		self._container = gtk.VBox(False, 5)
		self._controls = gtk.HBox(False, 5)

		separator = gtk.HSeparator()

		# pack interface
		self._container.pack_end(separator, False, False, 0)
		self._container.pack_end(self._controls, False, False, 0)