import functools
import json

def set_headers_decorator(func):
    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        kwargs.setdefault(
            'headers',
            {
                 'user-agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.131 Safari/537.36',
                 'accept-encoding': 'gzip, deflate, br',
                'accept-language': 'en-GB,en-US;q=0.9,en;q=0.8',
            },
        )
        # another option
        # kwargs.setdefault('headers', {})
        # kwargs['headers'].update(...)

        # yet another option
        # kwargs.setdefault('headers', {})
        # for k, v in {...}.items():
        #      kwargs['headers'].setdefault(k, v)

        return func(*args, **kwargs, headers=headers)
    return wrapper

@set_headers_decorator
def get_url(*args, **kwargs):
    import requests
    return requests.get(*args, **kwargs)

print(json.loads(get_url("http://ifconfig.co/json").content))