Move an if from the printer

This if is already present in `Mv_latex_str`, and it makes more sense to push it into `Mv_str` to match.

Author: eric-wieser

galgebra/mv.py

@@ -585,6 +585,10 @@ def __getitem__(self, key):
 
     def Mv_str(self, print_obj):
         global print_replace_old, print_replace_new
+
+        if self.obj == S.Zero:
+            return ZERO_STR
+
         if self.i_grade == 0:
             return print_obj.doprint(self.obj)
 
@@ -653,7 +657,7 @@ def Mv_str(self, print_obj):
 
     def Mv_latex_str(self, print_obj):
 
-        if self.obj == 0:
+        if self.obj == S.Zero:
             return ZERO_STR
 
         first_line = True

galgebra/printer.py

@@ -371,10 +371,7 @@ def _print_Matrix(self, expr):
         return out_str
 
     def _print_Mv(self, expr):
-        if expr.obj == S(0):
-            return ZERO_STR
-        else:
-            return expr.Mv_str(self)
+        return expr.Mv_str(self)
 
     def _print_Pdop(self, expr):
         return expr.Pdop_str(self)
@@ -937,10 +934,7 @@ def _print_Derivative(self, expr):
         return s
 
     def _print_Mv(self, expr):
-        if expr.obj == S(0):
-            return ZERO_STR
-        else:
-            return expr.Mv_latex_str(self)
+        return expr.Mv_latex_str(self)
 
     def _print_Pdop(self, expr):
         return expr.Pdop_latex_str(self)