remove is_GapElement from number fields code

Author: dimpase

src/sage/rings/number_field/number_field.py

@@ -159,6 +159,8 @@
 from sage.modules.free_module_element import vector
 from sage.rings.real_mpfr import RR
 
+from sage.interfaces.abc import GapElement
+
 _NumberFields = NumberFields()
 
 
@@ -1819,7 +1821,7 @@ def _element_constructor_(self, x, check=True):
                 raise TypeError("%s has unsupported PARI type %s" % (x, x.type()))
             x = self.absolute_polynomial().parent()(x)
             return self._element_class(self, x)
-        elif sage.interfaces.gap.is_GapElement(x):
+        elif isinstance(x, GapElement):
             s = x._sage_repr()
             if self.variable_name() in s:
                 return self._convert_from_str(s)
@@ -11143,8 +11145,7 @@ def _element_constructor_(self, x, check=True):
                 return NumberField_absolute._element_constructor_(self, x)
         elif isinstance(x, pari_gen):
             return NumberField_absolute._element_constructor_(self, x, check=check)
-        elif (sage.interfaces.gap.is_GapElement(x) or
-              isinstance(x, sage.libs.gap.element.GapElement)):
+        elif isinstance(x, (sage.libs.gap.element.GapElement, GapElement)):
             return self._coerce_from_gap(x)
         elif isinstance(x, str):
             return self._convert_from_str(x)