in coinrun/coinrun.cpp [290:297]
bool has_vertical_space(float x, float y, bool crate_counts)
{
return !(
is_wall(get_elem(x + .1, y)) || is_wall(get_elem(x + .9, y))
|| (crate_counts && is_crat(get_elem(x + .1, y)))
|| (crate_counts && is_crat(get_elem(x + .9, y)))
);
}