class_docstr: UnitSystem represents a coherent set of units.
  
  A unit system is basically a dimension system with notions of scales. Many
  of the methods are defined in the same way.
  
  It is much better if all base units have a symbol.
class_docstr_tok: ["UnitSystem","represents","a","coherent","set","of","units",".","A","unit","system","is","basically","a","dimension","system","with","notions","of","scales",".","Many","of","the","methods","are","defined","in","the","same","way",".","It","is","much","better","if","all","base","units","have","a","symbol","."]
code: def get_quantity_scale_factor(self, unit):
      qsfm = self.get_dimension_system()._quantity_scale_factors
      if unit in qsfm:
          return qsfm[unit]
      return super().get_quantity_scale_factor(unit)
  
imports: from typing import Dict, Set
  from sympy.core.add import Add
  from sympy.core.function import Derivative, Function
  from sympy.core.mul import Mul
  from sympy.core.power import Pow
  from sympy.core.singleton import S
  from sympy.physics.units.dimensions import _QuantityMapper
  from sympy.physics.units.quantities import Quantity
  from .dimensions import Dimension
label_desc: Use image node_id 7 for calling the UnitSystem obj's underlying member method code with example usage: obj.get_quantity_scale_factor(unit) and returns: super, qsfm