code: def firstChild(hot_map, index):
          ''' Return the first child of the node indicated by index. '''
          children = hot_map[index][2]
          if children:
              return children[0][1]
          else:
              return hot_map[index][1f firstChild(hot_map, index):
          ''' Return the first child of the node indicated by index. '''
          children = hot_map[index][2]
          if children:
              return children[0][1]
          else:
              return hot_map[index][1]
docs: Return the first child of the node indicated by index.