def size(f, unit='B', fileStore=None):
    """
    Returns the size of a file in bytes.

    :param f: Filename
    :param unit: Return the byte size in these units (gigabytes, etc.).
    :return:
    """
    divisor = return_bytes(unit)
    fileID = process_infile(f, fileStore)[0]
    return fileID.size / divisor