def replace_item(obj, key, replace_value):
    """
    Recursively replaces any matching key in a dictionary with a specified replacement
    value.
    
    Args:
        obj (dict): Dictionary where item is being replaced.
        key (obj): Key to replace in dictionary.
        replace_value (obj): What to replace the key with.
    
    Returns:
        dict: Dictionary with everything of that key replaced with the specified value.
    """
    for k, v in obj.items():
        if isinstance(v, dict):
            obj[k] = replace_item(v, key, replace_value)
    if key in obj:
        obj[key] = replace_value
    return obj