def rename_variables(self, *, implied=True, verbose=True, **kwargs):
        """Rename a set of variables.

        Parameters
        ----------
        kwargs
            Keyword arguments of the form current:'new'.
        implied : boolean (optional)
            Toggle inclusion of other variables that start with the same
            name. Default is True.
        verbose : boolean (optional)
            Toggle talkback. Default is True
        """
        # find all of the implied variables
        kwargs = collections.OrderedDict(kwargs)
        if implied:
            new = collections.OrderedDict()
            for k, v in kwargs.items():
                for n in self.variable_names:
                    if n.startswith(k):
                        new[n] = n.replace(k, v, 1)
            kwargs = new
        # ensure that items will remain unique
        changed = kwargs.keys()
        for k, v in kwargs.items():
            if v not in changed and v in self.keys():
                raise wt_exceptions.NameNotUniqueError(v)
        # compile references to items that are changing
        new = {}
        for k, v in kwargs.items():
            obj = self[k]
            index = self.variable_names.index(k)
            # rename
            new[v] = obj, index
            Group._instances.pop(obj.fullpath, None)
            obj.natural_name = str(v)
            # remove old references
            del self[k]
        # apply new references
        names = list(self.variable_names)
        for v, value in new.items():
            obj, index = value
            self[v] = obj
            names[index] = v
        self.variable_names = names
        units = self.units
        new = list(self.axis_expressions)
        for i, v in enumerate(kwargs.keys()):
            for j, n in enumerate(new):
                new[j] = n.replace(v, "{%i}" % i)
        for i, n in enumerate(new):
            new[i] = n.format(*kwargs.values())
        self.transform(*new)
        for a, u in zip(self._axes, units):
            a.convert(u)
        units = self.constant_units
        new = list(self.constant_expressions)
        for i, v in enumerate(kwargs.keys()):
            for j, n in enumerate(new):
                new[j] = n.replace(v, "{%i}" % i)
        for i, n in enumerate(new):
            new[i] = n.format(*kwargs.values())
        self.set_constants(*new)
        for c, u in zip(self._constants, units):
            c.convert(u)
        # finish
        if verbose:
            print("{0} variable(s) renamed:".format(len(kwargs)))
            for k, v in kwargs.items():
                print("  {0} --> {1}".format(k, v))
Rename a set of variables.

        Parameters
        ----------
        kwargs
            Keyword arguments of the form current:'new'.
        implied : boolean (optional)
            Toggle inclusion of other variables that start with the same
            name. Default is True.
        verbose : boolean (optional)
            Toggle talkback. Default is True