How to use the chameleon.core.types.parts function in Chameleon

def content(self):
            content = self._content
            if content is not None:
                if isinstance(content, types.escape):
                    return types.escape((types.value(self.content_symbol),))
                return types.parts((types.value(self.content_symbol),))

def __init__(self, parts, variable=None):
        if not isinstance(parts, types.parts):
            parts = types.parts((parts,))

        self.parts = parts
        self.variable = variable

stream.symbol_mapping.update(value.symbol_mapping)

        if isinstance(value, types.template):
            value = types.value(value % symbols)
        if isinstance(value, types.value):
            stream.write("%s = %s" % (variable, value))
        elif isinstance(value, types.join):
            parts = []
            _v_count = 0

            for part in value:
                if isinstance(part, types.expression):
                    stream.symbol_mapping.update(part.symbol_mapping)
                if isinstance(part, types.template):
                    part = types.value(part % symbols)
                if isinstance(part, (types.parts, types.join)):
                    _v = stream.save()
                    assign = Assign(part, _v)
                    assign.begin(stream)
                    assign.end(stream)
                    _v_count +=1
                    parts.append(_v)
                elif isinstance(part, types.value):
                    parts.append(part)
                elif isinstance(part, unicode):
                    if stream.encoding:
                        parts.append(repr(part.encode(stream.encoding)))
                    else:
                        parts.append(repr(part))
                elif isinstance(part, str):
                    parts.append(repr(part))
                else:

value.label = expr
            parts.append(value)
            translator = self
            
            i = j + 1

        value = translator.translate("", escape)
        if value is not None:
            value.label = ""
            parts.append(value)

        if len(parts) == 1:
            return parts[0]

        return types.parts(parts)

...     def translate(self, string, escape=None):
        ...         if string: return types.value(string)

        >>> tales = MockExpressionTranslator().tales
                
        >>> tales('a')
        value('a')

        >>> tales('a|b')
        parts(value('a'), value('b'))
        """

        string = string.replace('\n', '').strip()

        if not string:
            return types.parts()

        parts = []

        # default translator is ``self``
        translator = self

        i = j = 0
        while i < len(string):
            match = self.re_pragma.match(string[i:])
            if match is not None:
                pragma = match.group('pragma')
                new_translator = self.pragma(pragma)
                if new_translator is not None:
                    translator = new_translator
                    i += match.end()
                    if translator.recursive:

match = self.re_pragma.match(string[i:])
            if match is not None:
                pragma = match.group('pragma')
                new_translator = self.pragma(pragma)
                if new_translator is not None:
                    translator = new_translator
                    i += match.end()
                    if translator.recursive:
                        value = translator.tales(string[i:])
                        if parts:
                            if isinstance(value, types.parts):
                                parts.extend(value)
                            else:
                                parts.append(value)

                            return types.parts(parts)
                        return value
                    continue

            j = string.find('|', j + 1)
            if j == -1:
                j = len(string)

            expr = string[i:j]

            try:
                value = translator.translate(expr, escape)
            except SyntaxError:
                if j < len(string):
                    continue
                raise

# default translator is ``self``
        translator = self

        i = j = 0
        while i < len(string):
            match = self.re_pragma.match(string[i:])
            if match is not None:
                pragma = match.group('pragma')
                new_translator = self.pragma(pragma)
                if new_translator is not None:
                    translator = new_translator
                    i += match.end()
                    if translator.recursive:
                        value = translator.tales(string[i:])
                        if parts:
                            if isinstance(value, types.parts):
                                parts.extend(value)
                            else:
                                parts.append(value)

                            return types.parts(parts)
                        return value
                    continue

            j = string.find('|', j + 1)
            if j == -1:
                j = len(string)

            expr = string[i:j]

            try:
                value = translator.translate(expr, escape)