code: def _check_ising_linear_ranges(linear_ranges, graph):
          
          if linear_ranges is None:
              linear_ranges = {}
  
          for v in graph:
              if v in linear_ranges:
                  # check
                  linear_ranges[v] = Specification._check_range(linear_ranges[v])
              else:
                  # set default
                  linear_ranges[v] = [-2, 2]
  
          return linear_ranges
docs: check correctness/populate defaults for ising_linear_ranges.