gh-73487: Convert _decimal to use Argument Clinic (part 4)

[skirpichev]

• Issue: decimal: Use Argument Clinic #73487

[skirpichev]

Docstrings diff:

--- ref.txt 2025-08-20 12:30:34.001295564 +0300
+++ patch.txt   2025-08-20 12:29:57.118168737 +0300
@@ -108,13 +108,16 @@
      |  Methods defined here:
      |
      |  Etiny(self, /)
-     |      Return a value equal to Emin - prec + 1, which is the minimum exponent value
-     |      for subnormal results.  When underflow occurs, the exponent is set to Etiny.
+     |      Return a value equal to Emin - prec + 1.
+     |
+     |      This is the minimum exponent value for subnormal results.  When
+     |      underflow occurs, the exponent is set to Etiny.
      |
      |  Etop(self, /)
-     |      Return a value equal to Emax - prec + 1.  This is the maximum exponent
-     |      if the _clamp field of the context is set to 1 (IEEE clamp mode).  Etop()
-     |      must not be negative.
+     |      Return a value equal to Emax - prec + 1.
+     |
+     |      This is the maximum exponent if the _clamp field of the context is set
+     |      to 1 (IEEE clamp mode).  Etop() must not be negative.
      |
      |  __copy__(self, /)
      |
@@ -437,10 +440,12 @@
     class Decimal(builtins.object)
      |  Decimal(value='0', context=None)
      |
-     |  Construct a new Decimal object. 'value' can be an integer, string, tuple,
-     |  or another Decimal object. If no value is given, return Decimal('0'). The
-     |  context does not affect the conversion and is only passed to determine if
-     |  the InvalidOperation trap is active.
+     |  Construct a new Decimal object.
+     |
+     |  value can be an integer, string, tuple, or another Decimal object.  If
+     |  no value is given, return Decimal('0'). The context does not affect
+     |  the conversion and is only passed to determine if the InvalidOperation
+     |  trap is active.
      |
      |  Methods defined here:
      |
@@ -454,12 +459,14 @@
      |      True if self else False
      |
      |  __ceil__(self, /)
+     |      Return the ceiling as an Integral.
      |
      |  __complex__(self, /)
+     |      Convert this value to exact type complex.
      |
      |  __copy__(self, /)
      |
-     |  __deepcopy__(self, object, /)
+     |  __deepcopy__(self, memo, /)
      |
      |  __divmod__(self, value, /)
      |      Return divmod(self, value).
@@ -471,6 +478,7 @@
      |      float(self)
      |
      |  __floor__(self, /)
+     |      Return the floor as an Integral.
      |
      |  __floordiv__(self, value, /)
      |      Return self//value.
@@ -524,7 +532,7 @@
      |      Return divmod(value, self).
      |
      |  __reduce__(self, /)
-     |      Helper for pickle.
+     |      Return state information for pickling.
      |
      |  __repr__(self, /)
      |      Return repr(self).
@@ -538,7 +546,8 @@
      |  __rmul__(self, value, /)
      |      Return value*self.
      |
-     |  __round__(...)
+     |  __round__(self, ndigits=<unrepresentable>, /)
+     |      Return the Integral closest to self, rounding half toward even.
      |
      |  __rpow__(self, value, mod=None, /)
      |      Return pow(value, self, mod).
@@ -550,7 +559,7 @@
      |      Return value/self.
      |
      |  __sizeof__(self, /)
-     |      Size of object in memory, in bytes.
+     |      Returns size in memory, in bytes
      |
      |  __str__(self, /)
      |      Return str(self).
@@ -562,6 +571,7 @@
      |      Return self/value.
      |
      |  __trunc__(self, /)
+     |      Return the Integral closest to x between 0 and x.
      |
      |  adjusted(self, /)
      |      Return the adjusted exponent (exp + digits - 1) of the number.