ExtPower[Dual]FreeModule, FiniteRankDualFreeModule: Add docstring to construction method

Author: Matthias Koeppe

src/sage/tensor/modules/ext_pow_free_module.py

@@ -253,6 +253,10 @@ def __init__(self, fmodule, degree, name=None, latex_name=None):
 
     def construction(self):
         r"""
+        Return the functorial construction of ``self``.
+
+        This implementation just returns ``None``, as no functorial construction is implemented.
+
         TESTS::
 
             sage: from sage.tensor.modules.ext_pow_free_module import ExtPowerFreeModule
@@ -634,6 +638,10 @@ def __init__(self, fmodule, degree, name=None, latex_name=None):
 
     def construction(self):
         r"""
+        Return the functorial construction of ``self``.
+
+        This implementation just returns ``None``, as no functorial construction is implemented.
+
         TESTS::
 
             sage: from sage.tensor.modules.ext_pow_free_module import ExtPowerDualFreeModule

src/sage/tensor/modules/finite_rank_free_module.py

@@ -3101,6 +3101,10 @@ def __init__(self, fmodule, name=None, latex_name=None):
 
     def construction(self):
         r"""
+        Return the functorial construction of ``self``.
+
+        This implementation just returns ``None``, as no functorial construction is implemented.
+
         TESTS::
 
             sage: from sage.tensor.modules.ext_pow_free_module import ExtPowerDualFreeModule