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": "target_heart_rate", "description": "Calculates the target heart rate range for cardiovascular exercise using the Karvonen method based on the user's age and fitness level.", "parameters": {"age": {"description": "The age of the user in years.", "type": "int", "default": "27"}, "fitness_level": {"description": "The fitness level of the user. Acceptable values are \"beginner\", \"intermediate\", and \"advanced\".", "type": "str", "default": "beginner"}}}]
What is the target heart rate range for a 25-year-old advanced athlete and a 50-year-old beginner?
user
assistant
[{"name": "target_heart_rate", "arguments": {"age": 25, "fitness_level": "advanced"}}, {"name": "target_heart_rate", "arguments": {"age": 50, "fitness_level": "beginner"}}]