Method ok_if_can_unload

battlecode-engine/src/world.rs:1797–1809

(&self, structure_id: UnitID, direction: Direction)

    }

    fn ok_if_can_unload(&self, structure_id: UnitID, direction: Direction)
                        -> Result<(), GameError> {
        let structure = self.my_unit(structure_id)?;
        structure.ok_if_on_map()?;
        structure.ok_if_can_unload_unit()?;
        let robot = self.my_unit(structure.structure_garrison()?[0])?;
        let loc = structure.location().map_location()?.add(direction);
        if !self.is_occupiable(loc)? {
            Err(GameError::LocationNotEmpty)?;
        }
        robot.ok_if_move_ready()?;
        Ok(())
    }

    /// Tests whether the given structure is able to unload a unit in the
    /// given direction. There must be space in that direction, and the unit