def METHOD_NAME(self, array_keys=None):
    """Get the least common multiple of the voxel sizes in this spec.
    Args:
        array_keys (list of :class:`ArrayKey`, optional): If given,
            consider only the given array types.
    """
    if array_keys is None:
        array_keys = self.array_specs.keys()
    if not array_keys:
        return None
    lcm_voxel_size = None
    for key in array_keys:
        voxel_size = self.array_specs[key].voxel_size
        if voxel_size is None:
            continue
        if lcm_voxel_size is None:
            lcm_voxel_size = voxel_size
        else:
            lcm_voxel_size = Coordinate(
                (
                    a * b // math.gcd(a, b)
                    for a, b in zip(lcm_voxel_size, voxel_size)
                )
            )
    return lcm_voxel_size