What type of punctuation should be used at the end of the following sentence?
Let's look at the bird
A period should be used at the end of that sentence: Let's look at the bird.
Complete the following task based on the instruction and optional input provided.### Instruction:
What type of punctuation should be used at the end of the following sentence?

### Input:
Let's look at the bird

### Output:
A period should be used at the end of that sentence: Let's look at the bird.