adding create_new to args StateParamScheduler (#2404)

* adding create_new to args StateParamScheduler

* autopep8 fix

Co-authored-by: bibhabasumohapatra <[email protected]>

Author: bibhabasumohapatra

Diff for: ignite/handlers/state_param_scheduler.py

@@ -123,6 +123,10 @@ class LambdaStateScheduler(StateParamScheduler):
         param_name: name of parameter to update.
         save_history: whether to log the parameter values to
             `engine.state.param_history`, (default=False).
+        create_new: whether to create ``param_name`` on
+            ``engine.state`` taking into account whether
+            ``param_name`` attribute already exists or not.
+            Overrides existing attribute by default, (default=False).
 
     Examples:
 
@@ -200,6 +204,10 @@ class PiecewiseLinearStateScheduler(StateParamScheduler):
         param_name: name of parameter to update.
         save_history: whether to log the parameter values to
             `engine.state.param_history`, (default=False).
+        create_new: whether to create ``param_name`` on
+            ``engine.state`` taking into account whether
+            ``param_name`` attribute already exists or not.
+            Overrides existing attribute by default, (default=False).
 
     Examples:
 
@@ -320,6 +328,10 @@ class ExpStateScheduler(StateParamScheduler):
         param_name: name of parameter to update.
         save_history: whether to log the parameter values to
             `engine.state.param_history`, (default=False).
+        create_new: whether to create ``param_name`` on
+            ``engine.state`` taking into account whether
+            ``param_name`` attribute already exists or not.
+            Overrides existing attribute by default, (default=False).
 
     Examples:
 
@@ -383,6 +395,10 @@ class StepStateScheduler(StateParamScheduler):
         param_name: name of parameter to update.
         save_history: whether to log the parameter values to
             `engine.state.param_history`, (default=False).
+        create_new: whether to create ``param_name`` on
+            ``engine.state`` taking into account whether
+            ``param_name`` attribute already exists or not.
+            Overrides existing attribute by default, (default=False).
 
     Examples:
 
@@ -457,6 +473,10 @@ class MultiStepStateScheduler(StateParamScheduler):
         param_name: name of parameter to update.
         save_history: whether to log the parameter values to
             `engine.state.param_history`, (default=False).
+        create_new: whether to create ``param_name`` on
+            ``engine.state`` taking into account whether
+            ``param_name`` attribute already exists or not.
+            Overrides existing attribute by default, (default=False).
 
     Examples: