class PenModification: Modification
placeable: {entity: Entity, factory: fun(): Entity}
locations: SparseGrid

A sparse grid class that stores data using hashed coordinates. Similar to a SparseMap except here there is only one entry per grid coordinate. This is suitable for stuff like Cells.

__new(
    self: PenModification,
    placeable: {entity: Entity, factory: fun(): Entity},
    locations: SparseGrid
)