InvalidPolicyConfig: Module for policy 'KerasPolicy' could not be loaded. code example

Example: InvalidPolicyConfig: Module for policy 'KerasPolicy' could not be loaded. Please make sure the name is a valid policy.

language: en

pipeline:
- name: WhitespaceTokenizer
- name: RegexFeaturizer
- name: LexicalSyntacticFeaturizer
- name: CountVectorsFeaturizer
- name: CountVectorsFeaturizer
  analyzer: char_wb
  min_ngram: 1
  max_ngram: 4
- name: DIETClassifier
  epochs: 100
- name: EntitySynonymMapper
- name: ResponseSelector
  epochs: 100
- name: FallbackClassifier
  threshold: 0.3
  ambiguity_threshold: 0.1

policies:
- name: MemoizationPolicy
- name: TEDPolicy
  max_history: 5
  epochs: 10