code: def show(self, eq, value=None):
          
          if eq in ['f', 'x']:
              key = 'unamex'
          elif eq in ['g', 'y']:
              key = 'unamey'
  
          if value:
              value = list(value)
          else:
              value = list(self.__dict__[eq])
  
          out = ''
          for name, val, idx in zip(self.system.varname.__dict__[key], value,
                                    range(len(value))):
              out += '{:20s} [{:>12.4f}] {:g}\n'.format(name, val, idx)
          return out
docs: Show equation or variable array along with the names