code: def get_primary_or_secondary(self, component, return_ind=False):
          
          parent = self.get_parent_of(component)
          if parent is None:
              # then this is a single component, not in a binary
              return 'primary'
  
          children_of_parent = self.get_children_of(parent)
  
          ind = children_of_parent.index(component)
  
          if ind > 1:
              return None
  
          if return_ind:
              return ind + 1
  
          return ['primary', 'secondary'][ind]
docs: return whether a given component is the 'primary' or 'secondary'
          component in its parent orbit