def astar(world_map, start_cell, end_cell):

"""

Returns a list of Cell as a path from the given start to the given end in the given world_map.

The best path navigates the obstacles (but not other avatars, as they're assumed to be moving).

For explanation of the A* pathfinding, see the medium post at the top.

def _get_adjacent_cells(current_node, world_map):

adj = []

# we move only in 4 directions

for direction in ALL_DIRECTIONS:

# make sure the cell is within the grid