Revert "fix N (#106)"

This reverts commit 66bd00f.

CHANGES.rst

@@ -35,8 +35,8 @@ Internals
 Bugs
 ++++
 
-* ``First``, ``Rest`` and  ``Last`` now handle invalid arguments (issue #104).
-* ``N`` now handles properly the conversion of large integers to PrecisionReal (issue #103).
+* ``First``, ``Rest`` and  ``Last`` now handle invalid arguments.
+  
 
 4.0.1
 -----

mathics/core/atoms.py

@@ -165,11 +165,9 @@ def to_python(self, *args, **kwargs):
 
     def round(self, d=None) -> typing.Union["MachineReal", "PrecisionReal"]:
         if d is None:
-            try:
-                return MachineReal(float(self.value))
-            except:
-                d = 15
-        return PrecisionReal(sympy.Float(self.value, d))
+            return MachineReal(float(self.value))
+        else:
+            return PrecisionReal(sympy.Float(self.value, d))
 
     def get_int_value(self) -> int:
         return self.value