code: def validate_depth(self, depth: DepthDefinitionType) -> Optional[int]:
          
          if depth is not None:
              try:
                  depth = int(depth)
              except ValueError:
                  raise ValueError(f"Depth '{depth}' can't be converted to int.")
  
              if depth < 1:
                  raise ValueError(f"Depth '{depth}' isn't a positive number")
  
              return depth
          return None
docs: Converts the depth to int and validates that the value can be used.
  
          :raise ValueError: If the provided depth is not valid