text: """Implementation of :class:`CompositeDomain` class. """
  
  from __future__ import print_function, division
  
  from sympy.polys.domains.domain import Domain
  from sympy.polys.polyerrors import GeneratorsError
  
  from sympy.utilities import public
  
  
  @public
  class CompositeDomain(Domain):
      """Base class for composite domains, e.g. ZZ[x], ZZ(X). """
  
      is_Composite = True
  
      gens, ngens, symbols, domain = [None] * 4
  
      def inject(self, *symbols):
          """Inject generators into this domain. """
          if not (set(self.symbols) & set(symbols)):
              return self.__class__(self.domain, self.symbols + symbols, self.order)
          else:
              raise GeneratorsError(
                  "common generators in %s and %s" % (self.symbols, symbols)
              )
  