SpreadsheetExpressionEvaluationContext.removeEnvironmentValue return-…

src/main/java/walkingkooka/spreadsheet/expression/BasicSpreadsheetExpressionEvaluationContext.java

@@ -152,6 +152,12 @@ public <T> SpreadsheetExpressionEvaluationContext setEnvironmentValue(final Envi
         return this;
     }
 
+    @Override
+    public SpreadsheetExpressionEvaluationContext removeEnvironmentValue(final EnvironmentValueName<?> name) {
+        this.providerContext.removeEnvironmentValue(name);
+        return this;
+    }
+
     // SpreadsheetExpressionEvaluationContext............................................................................
 
     @Override

src/main/java/walkingkooka/spreadsheet/expression/LocalReferencesSpreadsheetExpressionEvaluationContext.java

@@ -374,6 +374,12 @@ public <T> SpreadsheetExpressionEvaluationContext setEnvironmentValue(final Envi
         return this;
     }
 
+    @Override
+    public SpreadsheetExpressionEvaluationContext removeEnvironmentValue(final EnvironmentValueName<?> name) {
+        this.context.removeEnvironmentValue(name);
+        return this;
+    }
+
     // Object...........................................................................................................
 
     @Override

src/main/java/walkingkooka/spreadsheet/expression/SpreadsheetExpressionEvaluationContext.java

@@ -217,6 +217,9 @@
     @Override
     <T> SpreadsheetExpressionEvaluationContext setEnvironmentValue(final EnvironmentValueName<T> name,
                                                                    final T value);
+
+    SpreadsheetExpressionEvaluationContext removeEnvironmentValue(final EnvironmentValueName<?> name);
+
     // validation.......................................................................................................
 
     /**