from typing import Dict, List


def bytes_to_strings(data: Dict[str, List[bytes]]) -> Dict[str, List[str]]:
    """Convert the attribute values from bytes to strings"""
    return {
        key: [b.decode() for b in val]
        for key, val in data.items()
    }


def strings_to_bytes(data: Dict[str, List[str]]) -> Dict[str, List[bytes]]:
    """Convert the attribute values from strings to bytes"""
    return {
        key: [b.encode() for b in val]
        for key, val in data.items()
    }


def dn_to_uid(dn: str) -> str:
    """Extract the UID from an LDAP DN.

    Examples:
        dn_to_uid('uid=ctdalek,ou=People,dc=csclub,dc=uwaterloo,dc=ca')
        -> 'ctdalek'
    """
    return dn.split(',', 1)[0].split('=')[1]