The conversation between human and AI assistant.
[|Human|] Identify the figure of speech used in the following sentence: “It was raining cats and dogs.”
[|AI|] The figure of speech used in the sentence "It was raining cats and dogs." is an idiom. This idiom means that it was raining very heavily.
[|Human|] 
Identify the figure of speech used in the following sentence: “It was raining cats and dogs.”