def METHOD_NAME(self, db):
    # First, insert some data for a subtype into nanofiltration entry
    db._cached_files["nanofiltration"]["subtype1"] = {
        "recovery_frac_mass_H2O": "overloaded",
        "new_param": True,
    }
    # Load data for subtype
    data = db.get_unit_operation_parameters("nanofiltration", subtype="subtype1")
    # Check data
    for k, v in data.items():
        if k == "recovery_frac_mass_H2O":
            assert v == "overloaded"
        elif k == "new_param":
            assert v is True
        else:
            # All other entries should match defaults
            assert v == db._cached_files["nanofiltration"]["default"][k]