from typing import Optional
from typing import Tuple


def parse_data_type_string(type_string: Optional[str]) -> Tuple[Optional[str], bool]:
    """Parse the data type string. Arrays are expressed in the form 'type[]'.

    e.g.
    - 'string' -> ('string', false)
    - 'string[]' -> ('string', true)
    """
    if not type_string:
        return None, False
    idx = type_string.find("[]")
    if idx == -1:
        return type_string, False
    return type_string[:idx], True