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

expr = self.tales(string[i:j], ';')
                except SyntaxError:
                    if string.rfind(';', i, j) > 0:
                        continue
                    raise

                break

            defines.append((var, expr))

            if j < 0:
                break

            i = j + 1

        return types.definitions(defines)

expr = self.expression(string[i:j])
                except SyntaxError, e:
                    if string.rfind(';', i, j) > 0:
                        continue
                    raise e
                
                break
                
            defines.append((var, expr))

            if j < 0:
                break
            
            i = j + 1

        return types.definitions(defines)

def assign(self):
            content = self._content
            if content is not None:
                definition = (
                    types.declaration((self.content_symbol,)),
                    content)
                return types.definitions((definition,))