code: def _get_priority_vars(objects, priority_arg, compat='equals'):
        # noqa
      if priority_arg is None:
          priority_vars = {}
      else:
          expanded = expand_variable_dicts([objects[priority_arg]])
          priority_vars = merge_variables(expanded, compat=compat)
      return priority_vars
docs: Extract the priority variable from a list of mappings.
  
      We need this method because in some cases the priority argument itself
      might have conflicting values (e.g., if it is a dict with two DataArray
      values with conflicting coordinate values).
  
      Parameters
      ----------
      objects : list of dictionaries of variables
          Dictionaries in which to find the priority variables.
      priority_arg : int or None
          Integer object whose variable should take priority.
      compat : {'identical', 'equals', 'broadcast_equals', 'no_conflicts'}, optional
          Compatibility checks to use when merging variables.
  
      Returns
      -------
      None, if priority_arg is None, or an OrderedDict with Variable objects as
      values indicating priority variables.