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","."]
docstr: Return the units of the system that do not have a prefix.
docstr_tok: ["Return","the","units","of","the","system","that","do","not","have","a","prefix","."]
code: def get_units_non_prefixed(self) -> tSet[Quantity]:
      """
      Return the units of the system that do not have a prefix.
      """
      return set(
          filter(
              lambda u: not u.is_prefixed
              and not u.is_physical_constant,
              self._units,
          )
      )
  
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 15 for calling the UnitSystem obj's underlying member method code with example usage: obj.get_units_non_prefixed() and returns: set