如何知道getsourcelines检查的源代码中函数声明的起始列？

import inspect
import ast

def get_function_start_column(func):
    source_lines, _ = inspect.getsourcelines(func)
    source_code = ''.join(source_lines)
    tree = ast.parse(source_code)

    for node in ast.walk(tree):
        if isinstance(node, ast.FunctionDef):
            return node.col_offset

    return -1  # 如果找不到函数声明，则返回-1

# 示例函数
def my_function():
    pass

start_column = get_function_start_column(my_function)
print(start_column)