from typing import Any


def repr_or_str(o: Any) -> str:
    """
    repr_or_str function
    Returns a string representation of the input:
    - If input is bytes returns the hex representation
    - If input is str returns the string
    - If input is None returns empty string

    :type o: ``Any``
    :param o: Input data (str or bytes)

    :return: String representation of the input
    :rtype: ``str``
    """
    if isinstance(o, str):
        return o
    elif isinstance(o, bytes):
        return o.hex()
    elif o is None:
        return ''

    return repr(o)