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 name of the system.
  
  If it does not exist, then it makes a list of symbols (or names) of
  the base dimensions.
docstr_tok: ["Return","the","name","of","the","system",".","If","it","does","not","exist",",","then","it","makes","a","list","of","symbols","(","or","names",")","of","the","base","dimensions","."]
code: def __str__(self):
      """
      Return the name of the system.
  
      If it does not exist, then it makes a list of symbols (or names) of
      the base dimensions.
      """
  
      if self.name != "":
          return self.name
      else:
          return "UnitSystem((%s))" % ", ".join(
              str(d) for d in self._base_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 2 for calling the UnitSystem obj's underlying member method code with example usage: obj.__str__() and returns: self, unknown