def get_initial_domains_by_genome_assembly(genome_assembly):
    """Get a list of defaults HiGlass data ranges for a file.
    Args:
        genome_assembly(string): Description of the genome assembly.
    Returns:
        A dict with these keys:
        initialXDomain(list): Contains 2 numbers. The HiGlass display will horizontally span all of these data points along the X axis. 0 would be the start of chr1, for example.
        initialYDomain(list): Contains 2 numbers. The HiGlass display will focus on the center of this data (for 2D views) or ignore initialYDomain entirely (for 1D views.)
    """

    # Create default view options.
    domain_size_by_genome_assembly = {
        "GRCm38": 2725521370,
        "GRCh38": 3088269832,
        "dm6": 137547960,
        "galGal5": 1022704034
    }

    domain_size = domain_size_by_genome_assembly.get(genome_assembly, 2000000000)

    domain_ranges = {
        "initialXDomain": [
            domain_size * -1 / 4,
            domain_size * 5 / 4
        ],
        "initialYDomain": [
            domain_size * -1 / 4,
            domain_size * 5 / 4
        ]
    }
    return domain_ranges