What is the idiom in this sentence?
He kept a cool head in the middle of the storm.
The idiom in the sentence is "kept a cool head," which means to remain calm and composed during a difficult or stressful situation.
Complete the following task based on the instruction and optional input provided.### Instruction:
What is the idiom in this sentence?

### Input:
He kept a cool head in the middle of the storm.

### Output:
The idiom in the sentence is "kept a cool head," which means to remain calm and composed during a difficult or stressful situation.