func (f *Field) IsBlocked(x, y int) bool {
	if x < 0 || fieldBlockNumX <= x {
		return true
	}
	if y < 0 {
		return false
	}
	if fieldBlockNumY <= y {
		return true
	}
	return f.blocks[x][y] != BlockTypeNone
}
func (f *Field) IsBlocked(x, y int) bool {
	if x < 0 || fieldBlockNumX <= x {
		return true
	}
	if y < 0 {
		return false
	}
	if fieldBlockNumY <= y {
		return true
	}
	return f.blocks[x][y] != BlockTypeNone
}
// IsBlocked returns a boolean value indicating whether
// there is a block at position (x, y) on the field.