Helper names that receive a slice of the evaluation context as an injected
first argument, mapped to the context key to inject. SafeExpression
prepends context[key] for these before calling the helper, so an expression
author still calls them with only their documented arguments — exactly as
PARENT_BOUND_HELPERS injects the owning parent.
Helper names that receive a slice of the evaluation context as an injected first argument, mapped to the context key to inject.
SafeExpressionprependscontext[key]for these before calling the helper, so an expression author still calls them with only their documented arguments — exactly as PARENT_BOUND_HELPERS injects the owningparent.