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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _get_priority_vars(objects, priority_arg, compat='equals'):
 """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. """
  # 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