def METHOD_NAME(flat_dict: Dict) -> Dict:
    """Converts flat dictionary separated by slashes to nested dictionary.
    Args:
        flat_dict (Dict): flat dictionary containing no sub-dictionary with keys
            separated by slashes. e.g. {'a':1, 'b/c':2}
    Returns:
        Dict: a nested dict.
    """
    nested_dict = {}
    for k, v in flat_dict.items():
        # Initially sub_dict is the main nested_dict, but we will continually update it to be the
        # sub-dictionary of sub_dict.
        sub_dict = nested_dict
        sub_keys = k.split('/')
        for sub_key in sub_keys[:-1]:
            if sub_key not in sub_dict:
                # Create a new sub-dictionary inside of sub_dict.
                sub_dict[sub_key] = {}
            # Change the sub_dict reference to be the sub-dictionary of sub_dict (i.e. go one level deeper).
            sub_dict = sub_dict[sub_key]
        # The last key in sub_keys does not map to a dict. It just maps to v.
        sub_dict[sub_keys[-1]] = v
    # Changes to sub_dict will be reflected in nested_dict, so we can just return nested_dict.
    return nested_dict