trailing changes (#887)

This PR fixes the `RealSign` docstring and removes a trailing
unreachable piece of code in the `eval_Sign` function.

Author: mmatera

mathics/builtin/arithmetic.py

@@ -1291,7 +1291,7 @@ def test(self, expr) -> bool:
 class RealSign(Builtin):
     """
     <url>
-        :Signum:
+        :Sign function:
         https://en.wikipedia.org/wiki/Sign_function</url> (<url>
         :WMA link:
         https://reference.wolfram.com/language/ref/RealSign.html

mathics/eval/arithmetic.py

@@ -319,49 +319,6 @@ def eval_complex_sign(n: BaseElement) -> Optional[BaseElement]:
     sign = eval_RealSign(expr)
     return sign or eval_complex_sign(expr)
 
-    if expr.has_form("Power", 2):
-        base, exp = expr.elements
-        if exp.is_zero:
-            return Integer1
-        if isinstance(exp, (Integer, Real, Rational)):
-            sign = eval_Sign(base) or Expression(SymbolSign, base)
-            return Expression(SymbolPower, sign, exp)
-        if isinstance(exp, Complex):
-            sign = eval_Sign(base) or Expression(SymbolSign, base)
-            return Expression(SymbolPower, sign, exp.real)
-        if test_arithmetic_expr(exp):
-            sign = eval_Sign(base) or Expression(SymbolSign, base)
-            return Expression(SymbolPower, sign, exp)
-        return None
-    if expr.get_head() is SymbolTimes:
-        abs_value = eval_Abs(eval_multiply_numbers(*expr.elements))
-        if abs_value is Integer1:
-            return expr
-        if abs_value is None:
-            return None
-        criteria = eval_add_numbers(abs_value, IntegerM1)
-        if test_zero_arithmetic_expr(criteria, numeric=True):
-            return expr
-        return None
-    if expr.get_head() is SymbolPlus:
-        abs_value = eval_Abs(eval_add_numbers(*expr.elements))
-        if abs_value is Integer1:
-            return expr
-        if abs_value is None:
-            return None
-        criteria = eval_add_numbers(abs_value, IntegerM1)
-        if test_zero_arithmetic_expr(criteria, numeric=True):
-            return expr
-        return None
-
-    if test_arithmetic_expr(expr):
-        if test_zero_arithmetic_expr(expr):
-            return Integer0
-        if test_positive_arithmetic_expr(expr):
-            return Integer1
-        if test_negative_arithmetic_expr(expr):
-            return IntegerM1
-
 
 def eval_mpmath_function(
     mpmath_function: Callable, *args: Number, prec: Optional[int] = None