You are given a code:

def main_solution(x):
    return ((x).capitalize() + ('wtk' + 'fev'))

Can you predict the output of `main_solution("xzpyd")` without writing any code? Please reason and put your final answer in the following json format: {"output": <your output>}, where <your output> should be the final string.
user
{"ref_input": {"x": "xzpyd"}, "ref_output": "Xzpydwtkfev", "ref_code": "def main_solution(x):\n    return ((x).capitalize() + ('wtk' + 'fev'))", "funcname": "main_solution"}
rule