def read_dictionary_one_to_set(file_path, file_name, order_pairs=False, col_indices=(0, 1), ignore_header=False):
    """
    Read two columns mapping file into a dictionary key --> set.\n
    Removes repeated values for each key.\n
    If order_pairs=True pairs are added in Lexicographical order: key < value
    """
    result = {}
    with open(file_path + file_name) as file:
        if ignore_header:
            file.readline()
        for line in file:
            fields = line.split('\t')
            if max(col_indices) >= len(fields):
                raise ValueError(f"File does not have the columns requested: {col_indices}")
            key, value = fields[col_indices[0]], fields[col_indices[1]]
            if order_pairs and key > value:
                key, value = value, key
            result.setdefault(key.strip(), set()).add(value.strip())
    return result