def add(self, elem, replace=False):
        """Add a requirement.

        :param elem: a string or :class:`Requirement` instance.
        :param replace: if `True`, packages in the set with the same name will
            be removed first.
        """
        if isinstance(elem, text_type):
            elem = Requirement.coerce(elem)
        if replace and elem in self:
            self.remove(elem)
        super(Requirements, self).add(elem)
def test():
    frame = Frame()
    frame.pack(fill=BOTH, expand=YES)
    if os.name == "nt":
        # Set default font for all widgets; use Windows typical default
        frame.option_add("*font", "Tahoma 8")
    # The editors
    entry = DiacriticalEntry(frame)
    entry.pack(fill=BOTH, expand=YES)
    text = DiacriticalText(frame, width=76, height=25, wrap=WORD)
    if os.name == "nt":
        # But this looks better than the default set above
        text.config(font="Arial 10")
    text.pack(fill=BOTH, expand=YES)
    text.focus()
    frame.master.title("Diacritical Editor")
    frame.mainloop()