Add support for custom variable in templates.
These variables are not system generated but will be given by user and can be used in template. Template should not break if these are not there
Function should be chain-able and should be used in child logger
Add support for custom variable in templates. These variables are not system generated but will be given by user and can be used in template. Template should not break if these are not there
Function should be chain-able and should be used in child logger