user: Could you calculate the sum of two binary numbers '0011' and '1100' for me?

Available functions:
name: add_binary_numbers
description: Adds two binary numbers.
parameters: type: dict
properties: a: type: string
description: The first binary number.
b: type: string
description: The second binary number.
required: a
b

Ground truth function call(s):
add_binary_numbers(a='0011',b='1100')