Minecraft wiki entry for Placed_feature, associated text: environment_scan—Scans blocks either up or down, until the target condition is met. Returns the block position for which the target condition matches. If no target can be found within the maximum number of steps, returns nothing.
 direction_of_search: One of up or down
 max_steps: Value between 1 and 32.
 target_condition: The block predicate that is searched for.
Block predicate[show]
 allowed_search_condition: (optional) If specified, each step must match this block position in order to continue the scan.
Block predicate[show]