trying Travis suggestions

Author: fchapoton

src/sage/rings/lazy_series.py

@@ -87,7 +87,7 @@
 #                  https://www.gnu.org/licenses/
 # ****************************************************************************
 
-from sage.structure.element import Element, parent
+from sage.structure.element import Element, parent, ModuleElement, RingElement
 from sage.structure.richcmp import op_EQ, op_NE
 from sage.functions.other import factorial
 from sage.arith.power import generic_power
@@ -114,7 +114,8 @@
     Stream_dirichlet_invert
 )
 
-class LazyModuleElement(Element):
+
+class LazyModuleElement(ModuleElement):
     r"""
     A lazy sequence with a module structure given by term-wise
     addition and scalar multiplication.
@@ -858,7 +859,6 @@ def _unicode_art_(self):
             return UnicodeArt('Uninitialized Lazy Laurent Series')
         return self._format_series(unicode_art, True)
 
-
     def change_ring(self, ring):
         r"""
         Return ``self`` with coefficients converted to elements of ``ring``.
@@ -1971,10 +1971,10 @@ def sqrt(self):
             sage: f*f - Z
             O(1/(8^s))
         """
-        return self ** (1/ZZ(2))
+        return self ** (~ZZ(2))
 
 
-class LazyCauchyProductSeries(LazyModuleElement):
+class LazyCauchyProductSeries(RingElement, LazyModuleElement):
     r"""
     A class for series where multiplication is the Cauchy product.