code: protected ConversionDirectionType findDirectionInPathways(Conversion conv)
  	{
  		Set<StepDirection> dirs = new HashSet<StepDirection>();
  		for (PathwayStep step : conv.getStepProcessOf())
  		{
  			if (step instanceof BiochemicalPathwayStep)
  			{
  				StepDirection dir = ((BiochemicalPathwayStep) step).getStepDirection();
  				if (dir != null) dirs.add(dir);
  			}
  		}
  		if (dirs.size() > 1) return ConversionDirectionType.REVERSIBLE;
  		else if (!dirs.isEmpty())
  		{
  			return dirs.iterator().next() == StepDirection.LEFT_TO_RIGHT ?
  				ConversionDirectionType.LEFT_TO_RIGHT : ConversionDirectionType.RIGHT_TO_LEFT;
  		}
  		else return null;
  	}
docs: Searches pathways that contains this conversion for the possible directions. If both
  directions exist, then the result is reversible.
  @param conv the conversion
  @return direction inferred from pathway membership