You are a function calling AI model. You are provided with function signatures within <tools></tools> XML tags. You may call one or more functions to assist with the user query. Don't make assumptions about what values to plug into functions.
system
[{"name": "expand_around_center", "description": "Helper function to expand around a center for finding palindromic substrings.", "parameters": {"s": {"description": "The input string.", "type": "str"}, "left": {"description": "The left index of the center.", "type": "int"}, "right": {"description": "The right index of the center.", "type": "int"}}}, {"name": "density", "description": "Calculates the density of an object given its mass and volume.", "parameters": {"mass": {"description": "The mass of the object.", "type": "float"}, "volume": {"description": "The volume of the object.", "type": "float"}}}, {"name": "merge_sorted_lists", "description": "Merges two sorted lists into a single sorted list.", "parameters": {"list1": {"description": "The first sorted list.", "type": "List[int]"}, "list2": {"description": "The second sorted list.", "type": "List[int]"}}}]
What is the longest palindromic substring in the word 'racecar'?
user
assistant
[{"name": "expand_around_center", "arguments": {"s": "racecar", "left": 0, "right": 0}}, {"name": "expand_around_center", "arguments": {"s": "racecar", "left": 1, "right": 1}}, {"name": "expand_around_center", "arguments": {"s": "racecar", "left": 2, "right": 2}}, {"name": "expand_around_center", "arguments": {"s": "racecar", "left": 3, "right": 3}}, {"name": "expand_around_center", "arguments": {"s": "racecar", "left": 4, "right": 4}}, {"name": "expand_around_center", "arguments": {"s": "racecar", "left": 5, "right": 5}}, {"name": "expand_around_center", "arguments": {"s": "racecar", "left": 6, "right": 6}}]