class_docstr: Locations must have the base master at the origin (ie. 0).
  
  If the extrapolate argument is set to True, then values are extrapolated
  outside the axis range.
  
    >>> from pprint import pprint
    >>> locations = [       {'wght':100},       {'wght':-100},       {'wght':-180},       {'wdth':+.3},       {'wght':+120,'wdth':.3},       {'wght':+120,'wdth':.2},       {},       {'wght':+180,'wdth':.3},       {'wght':+180},       ]
    >>> model = VariationModel(locations, axisOrder=['wght'])
    >>> pprint(model.locations)
    [{},
     {'wght': -100},
     {'wght': -180},
     {'wght': 100},
     {'wght': 180},
     {'wdth': 0.3},
     {'wdth': 0.3, 'wght': 180},
     {'wdth': 0.3, 'wght': 120},
     {'wdth': 0.2, 'wght': 120}]
    >>> pprint(model.deltaWeights)
    [{},
     {0: 1.0},
     {0: 1.0},
     {0: 1.0},
     {0: 1.0},
     {0: 1.0},
     {0: 1.0, 4: 1.0, 5: 1.0},
     {0: 1.0, 3: 0.75, 4: 0.25, 5: 1.0, 6: 0.6666666666666666},
     {0: 1.0,
      3: 0.75,
      4: 0.25,
      5: 0.6666666666666667,
      6: 0.4444444444444445,
      7: 0.6666666666666667}]
code: def _computeDeltaWeights(self):
      self.deltaWeights = []
      for i, loc in enumerate(self.locations):
          deltaWeight = {}
          # Walk over previous masters now, populate deltaWeight
          for j, support in enumerate(self.supports[:i]):
              scalar = supportScalar(loc, support)
              if scalar:
                  deltaWeight[j] = scalar
          self.deltaWeights.append(deltaWeight)
  
imports: from fontTools.misc.roundTools import noRound
  from .errors import VariationModelError
label_desc: Use image node_id 8 for calling the VariationModel obj's underlying member method code with example usage: obj._computeDeltaWeights() without return types