def wrap_loader_context(function, context):
    """Wrap functions that receive loader_context to contain the context
    "pre-loaded" and expose a interface that receives only one argument
    """
    if 'loader_context' in get_func_args(function):
        return partial(function, loader_context=context)
    else:
        return function
Wrap functions that receive loader_context to contain the context
    "pre-loaded" and expose a interface that receives only one argument
    
stackoverflow/venv/lib/python3.6/site-packages/scrapy/loader/common.py