code: def _project_TH3(self, hist: Hist) -> Any:
          
          # Axis length validation
          if len(self.projection_axes) < 1 or len(self.projection_axes) > 2:
              raise ValueError(len(self.projection_axes), "Invalid number of axes")
  
          # Need to concatenate the names of the axes together
          projection_axis_name = ""
          for axis in self.projection_axes:
              # Determine the axis name based on the name of the axis type.
              # [:1] returns just the first letter. For example, we could get "xy" if the first axis as
              # x_axis and the second was y_axis.
              # NOTE: Careful. This depends on the name of the enumerated values!!! Since this isn't terribly
              #       safe, we then perform additional validation on the same to ensure that it is one of the
              #       expected axis names.
              proj_axis_name = axis.axis_type.name[:1]
              if proj_axis_name not in ["x", "y", "z"]:
                  raise ValueError(f"Projection axis name {proj_axis_name} is not 'x', 'y', or 'z'. Please check your configuration.")
              projection_axis_name += proj_axis_name
  
          # Handle ROOT Project3D quirk...
          # 2D projection are called as (y, x, options), so we should reverse the order so it performs
          # as expected.
          # NOTE: This isn't well documented in TH3. It is instead described in THnBase.Projection(...)
          if len(self.projection_axes) == 2:
              # Reverse the axes
              projection_axis_name = projection_axis_name[::-1]
  
          # Do the actual projection
          logger.info(f"Projecting onto axes \"{projection_axis_name}\" from hist {hist.GetName()}")
          projected_hist = hist.Project3D(projection_axis_name)
  
          return projected_hist
docs: Perform the actual TH3 -> TH1 projection.
  
          This projection could be to 1D or 2D.
  
          Args:
              hist (ROOT.TH3): Histogram from which the projections should be performed.
          Returns:
              ROOT.TH1: The projected histogram.