def dtype_to_char(dtype):
    """Return character that represents data type."""
    dtype_char = {
        "complex64": "c",
        "complex128": "z",
        "float32": "f",
        "float64": "d",
        "int8": "b",
        "int16": "w",
        "int32": "i",
        "int64": "l",
    }
    if dtype in dtype_char:
        return dtype_char[dtype]
    else:
        return "X"