Remove domain restriction

Author: kwankyu

src/sage/modules/submodule.py

@@ -35,7 +35,7 @@
 # ****************************************************************************
 
 from sage.modules.free_module import (
-    FreeModule_ambient_domain,
+    FreeModule_ambient,
     Module_free_ambient,
     basis_seq,
 )
@@ -99,7 +99,7 @@ def __init__(self, ambient, gens, check=True, already_echelonized=False):
             sage: N.is_submodule(M)
             True
         """
-        if not isinstance(ambient, (FreeModule_ambient_domain, QuotientModule_free_ambient)):
+        if not isinstance(ambient, (FreeModule_ambient, QuotientModule_free_ambient)):
             raise TypeError("ambient (=%s) must be ambient or a quotient" % ambient)
         R = ambient.base_ring()
         degree = ambient.degree()