def read_file_str(file_path):
    """
    Read the target file string.

    Parameters
    ----------
    file_path : str
        Path of target file.

    Returns
    -------
    file_str : str
        The target string read.
    """
    with open(file_path, mode='r', encoding='utf-8') as f:
        file_str = f.read()
    return file_str
