Fix inaccurate wording in multiple decimal module docstrings (#155688)

Author: lpyu001

Lib/_pydecimal.py

@@ -5172,8 +5172,8 @@ def number_class(self, a):
         """Returns an indication of the class of the operand.
 
         The class is one of the following strings:
-          -sNaN
-          -NaN
+          sNaN
+          NaN
           -Infinity
           -Normal
           -Subnormal
@@ -5682,8 +5682,9 @@ def to_integral_value(self, a):
         When the operand has a negative exponent, the result is the same
         as using the quantize() operation using the given operand as the
         left-hand-operand, 1E+0 as the right-hand-operand, and the precision
-        of the operand as the precision setting, except that no flags will
-        be set.  The rounding mode is taken from the context.
+        of the operand as the precision setting, except that the Inexact and
+        Rounded flags will not be set.  The rounding mode is taken from the
+        context.
 
         >>> ExtendedContext.to_integral_value(Decimal('2.1'))
         Decimal('2')

Modules/_decimal/_decimal.c

@@ -6789,7 +6789,7 @@ _decimal.Context.power
 Compute a**b.
 
 If 'a' is negative, then 'b' must be integral. The result will be
-inexact unless 'a' is integral and the result is finite and can be
+inexact unless 'b' is integral and the result is finite and can be
 expressed exactly in 'precision' digits.  In the Python version the
 result is always correctly rounded, in the C version the result is
 almost always correctly rounded.
@@ -6807,7 +6807,7 @@ restrictions hold:
 static PyObject *
 _decimal_Context_power_impl(PyObject *context, PyTypeObject *cls,
                             PyObject *base, PyObject *exp, PyObject *mod)
-/*[clinic end generated code: output=d06d40c37cdd69dc input=178a254468ec189b]*/
+/*[clinic end generated code: output=d06d40c37cdd69dc input=660210a6607ca4b0]*/
 {
     PyObject *a, *b, *c = NULL;
     PyObject *result;
@@ -7067,13 +7067,19 @@ _decimal_Context_apply_impl(PyObject *context, PyTypeObject *cls,
 /*[clinic input]
 _decimal.Context.canonical = _decimal.Context.is_normal
 
-Return a new instance of x.
+Returns the same Decimal object.
+
+As we do not have different encodings for the same number, the
+received object already is in its canonical form.
+
+>>> ExtendedContext.canonical(Decimal('2.50'))
+Decimal('2.50')
 [clinic start generated code]*/
 
 static PyObject *
 _decimal_Context_canonical_impl(PyObject *context, PyTypeObject *cls,
                                 PyObject *x)
-/*[clinic end generated code: output=f213e433e2032e5e input=025ecb106ac15bff]*/
+/*[clinic end generated code: output=f213e433e2032e5e input=d9f19ee3e7ed9433]*/
 {
     decimal_state *state = PyType_GetModuleState(cls);
     if (!PyDec_Check(state, x)) {